diff --git a/backend/internal/handler/auth_handler.go b/backend/internal/handler/auth_handler.go
index 03d87b7f..f8c294cc 100644
--- a/backend/internal/handler/auth_handler.go
+++ b/backend/internal/handler/auth_handler.go
@@ -5130,6 +5130,13 @@ func (h *AuthHandler) GetConsentRequest(c *fiber.Ctx) error {
 		"scopes", consentRequest.RequestedScope,
 	)
 
+	profile, err := h.resolveCurrentProfile(c)
+	if err == nil && profile != nil {
+		if !isClientTenantAccessAllowed(profile, consentRequest.Client) {
+			return tenantNotAllowedError(c)
+		}
+	}
+
 	// [New] 로컬 DB에서 기존 동의 내역 확인 (강제 자동 승인 전략)
 	// Hydra가 skip을 주지 않더라도, 우리 DB에 이미 기록이 있다면 승인 처리함
 	if !consentRequest.Skip && h.ConsentRepo != nil && consentRequest.Subject != "" {
@@ -5333,6 +5340,13 @@ func (h *AuthHandler) AcceptConsentRequest(c *fiber.Ctx) error {
 		consentRequest.RequestedScope = filteredScopes
 	}
 
+	profile, err := h.resolveCurrentProfile(c)
+	if err == nil && profile != nil {
+		if !isClientTenantAccessAllowed(profile, consentRequest.Client) {
+			return tenantNotAllowedError(c)
+		}
+	}
+
 	// 3. Hydra에 승인 요청
 	if consentRequest.Subject == "" {
 		return fiber.NewError(fiber.StatusInternalServerError, "Consent subject missing")
@@ -5470,6 +5484,15 @@ func (h *AuthHandler) AcceptOidcLoginRequest(c *fiber.Ctx) error {
 		}
 	}
 
+	profile, err := h.resolveCurrentProfile(c)
+	if loginReq != nil {
+		if err == nil && profile != nil {
+			if !isClientTenantAccessAllowed(profile, loginReq.Client) {
+				return tenantNotAllowedError(c)
+			}
+		}
+	}
+
 	subject, err := h.resolveConsentSubject(c)
 	if err != nil || subject == "" {
 		return fiber.NewError(fiber.StatusUnauthorized, "Authentication required")
@@ -5520,6 +5543,10 @@ func (h *AuthHandler) AcceptOidcLoginRequest(c *fiber.Ctx) error {
 }
 
 func (h *AuthHandler) resolveCurrentProfile(c *fiber.Ctx) (*domain.UserProfileResponse, error) {
+	if profile, ok := c.Locals("user_profile").(*domain.UserProfileResponse); ok && profile != nil {
+		return profile, nil
+	}
+
 	appEnv := strings.ToLower(os.Getenv("APP_ENV"))
 	isDev := appEnv == "dev" || appEnv == "development" || appEnv == ""
 
@@ -5608,16 +5635,18 @@ func (h *AuthHandler) resolveCurrentProfile(c *fiber.Ctx) (*domain.UserProfileRe
 	}
 
 	// Fetch Tenant Metadata if missing
-	if profile.Tenant == nil && profile.TenantID != nil && *profile.TenantID != "" {
-		if tenant, err := h.TenantService.GetTenant(c.Context(), *profile.TenantID); err == nil {
-			profile.Tenant = tenant
+	if h.TenantService != nil {
+		if profile.Tenant == nil && profile.TenantID != nil && *profile.TenantID != "" {
+			if tenant, err := h.TenantService.GetTenant(c.Context(), *profile.TenantID); err == nil {
+				profile.Tenant = tenant
+			}
 		}
-	}
-	if profile.Tenant == nil && profile.CompanyCode != "" {
-		if tenant, err := h.TenantService.GetTenantBySlug(c.Context(), profile.CompanyCode); err == nil && tenant != nil {
-			profile.Tenant = tenant
-			if profile.TenantID == nil || *profile.TenantID == "" {
-				profile.TenantID = &tenant.ID
+		if profile.Tenant == nil && profile.CompanyCode != "" {
+			if tenant, err := h.TenantService.GetTenantBySlug(c.Context(), profile.CompanyCode); err == nil && tenant != nil {
+				profile.Tenant = tenant
+				if profile.TenantID == nil || *profile.TenantID == "" {
+					profile.TenantID = &tenant.ID
+				}
 			}
 		}
 	}
diff --git a/backend/internal/handler/client_tenant_access.go b/backend/internal/handler/client_tenant_access.go
new file mode 100644
index 00000000..d58e2d36
--- /dev/null
+++ b/backend/internal/handler/client_tenant_access.go
@@ -0,0 +1,144 @@
+package handler
+
+import (
+	"baron-sso-backend/internal/domain"
+	"errors"
+	"sort"
+	"strings"
+
+	"github.com/gofiber/fiber/v2"
+)
+
+const (
+	clientTenantAccessRestrictedKey = "tenant_access_restricted"
+	clientAllowedTenantsKey         = "allowed_tenants"
+)
+
+func normalizeClientTenantAccessMetadata(metadata map[string]interface{}) (map[string]interface{}, error) {
+	if metadata == nil {
+		metadata = map[string]interface{}{}
+	}
+
+	restricted := readMetadataBoolValue(metadata, clientTenantAccessRestrictedKey)
+	allowedTenants := normalizeMetadataStringSlice(metadata[clientAllowedTenantsKey])
+	ownerTenantID := normalizeMetadataString(metadata["tenant_id"])
+
+	if len(allowedTenants) > 0 {
+		restricted = true
+	}
+
+	if !restricted {
+		delete(metadata, clientAllowedTenantsKey)
+		metadata[clientTenantAccessRestrictedKey] = false
+		return metadata, nil
+	}
+
+	if ownerTenantID != "" {
+		allowedTenants = append(allowedTenants, ownerTenantID)
+	}
+	allowedTenants = uniqueSortedStrings(allowedTenants)
+	if len(allowedTenants) == 0 {
+		return nil, errors.New("allowed_tenants is required when tenant_access_restricted is enabled")
+	}
+
+	metadata[clientTenantAccessRestrictedKey] = true
+	metadata[clientAllowedTenantsKey] = allowedTenants
+	return metadata, nil
+}
+
+func clientTenantAccessRestricted(metadata map[string]interface{}) bool {
+	if metadata == nil {
+		return false
+	}
+	if readMetadataBoolValue(metadata, clientTenantAccessRestrictedKey) {
+		return true
+	}
+	return len(normalizeMetadataStringSlice(metadata[clientAllowedTenantsKey])) > 0
+}
+
+func clientAllowedTenants(metadata map[string]interface{}) []string {
+	if metadata == nil {
+		return nil
+	}
+	if !clientTenantAccessRestricted(metadata) {
+		return nil
+	}
+	return uniqueSortedStrings(normalizeMetadataStringSlice(metadata[clientAllowedTenantsKey]))
+}
+
+func normalizeMetadataStringSlice(raw any) []string {
+	switch value := raw.(type) {
+	case []string:
+		return uniqueSortedStrings(value)
+	case []any:
+		items := make([]string, 0, len(value))
+		for _, item := range value {
+			if s, ok := item.(string); ok {
+				items = append(items, s)
+			}
+		}
+		return uniqueSortedStrings(items)
+	default:
+		return nil
+	}
+}
+
+func normalizeMetadataString(raw any) string {
+	s, ok := raw.(string)
+	if !ok {
+		return ""
+	}
+	return strings.TrimSpace(s)
+}
+
+func uniqueSortedStrings(values []string) []string {
+	if len(values) == 0 {
+		return nil
+	}
+	seen := make(map[string]struct{}, len(values))
+	out := make([]string, 0, len(values))
+	for _, value := range values {
+		trimmed := strings.TrimSpace(value)
+		if trimmed == "" {
+			continue
+		}
+		if _, ok := seen[trimmed]; ok {
+			continue
+		}
+		seen[trimmed] = struct{}{}
+		out = append(out, trimmed)
+	}
+	sort.Strings(out)
+	return out
+}
+
+func clientTenantAccessAllowed(profile *domain.UserProfileResponse, client domain.HydraClient) bool {
+	if !clientTenantAccessRestricted(client.Metadata) {
+		return true
+	}
+	allowed := clientAllowedTenants(client.Metadata)
+	if len(allowed) == 0 {
+		return false
+	}
+	keys := manageableTenantKeysFromProfile(profile)
+	if len(keys) == 0 {
+		return false
+	}
+	for _, tenantID := range allowed {
+		if _, ok := keys[strings.ToLower(strings.TrimSpace(tenantID))]; ok {
+			return true
+		}
+	}
+	return false
+}
+
+func tenantNotAllowedError(c *fiber.Ctx) error {
+	return errorJSONCode(c, fiber.StatusForbidden, "tenant_not_allowed", "허용되지 않은 테넌트입니다.")
+}
+
+func isClientTenantAccessAllowed(profile *domain.UserProfileResponse, client domain.HydraClient) bool {
+	if profile == nil {
+		return false
+	}
+	return clientTenantAccessAllowed(profile, client)
+}
diff --git a/backend/internal/handler/client_tenant_access_test.go b/backend/internal/handler/client_tenant_access_test.go
new file mode 100644
index 00000000..51138845
--- /dev/null
+++ b/backend/internal/handler/client_tenant_access_test.go
@@ -0,0 +1,263 @@
+package handler
+
+import (
+	"baron-sso-backend/internal/domain"
+	"baron-sso-backend/internal/service"
+	"bytes"
+	"encoding/json"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/gofiber/fiber/v2"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestCreateClient_NormalizesTenantAccessMetadata(t *testing.T) {
+	var captured domain.HydraClient
+	ownerTenantID := "tenant-owner"
+
+	transport := roundTripFunc(func(r *http.Request) (*http.Response, error) {
+		if r.Method == http.MethodPost && r.URL.Path == "/clients" {
+			body, err := io.ReadAll(r.Body)
+			assert.NoError(t, err)
+			assert.NoError(t, json.Unmarshal(body, &captured))
+			return httpJSONAny(r, http.StatusCreated, map[string]any{
+				"client_id":                  captured.ClientID,
+				"client_name":                captured.ClientName,
+				"redirect_uris":              captured.RedirectURIs,
+				"grant_types":                captured.GrantTypes,
+				"response_types":             captured.ResponseTypes,
+				"scope":                      captured.Scope,
+				"token_endpoint_auth_method": captured.TokenEndpointAuthMethod,
+				"metadata":                   captured.Metadata,
+			}), nil
+		}
+		return httpJSONAny(r, http.StatusNotFound, nil), nil
+	})
+
+	h := &DevHandler{
+		Hydra: &service.HydraAdminService{
+			AdminURL:   "http://hydra.test",
+			HTTPClient: &http.Client{Transport: transport},
+		},
+		Keto: new(devMockKetoService),
+	}
+
+	app := fiber.New()
+	app.Use(func(c *fiber.Ctx) error {
+		c.Locals("user_profile", &domain.UserProfileResponse{
+			ID:       "user-1",
+			Role:     domain.RoleSuperAdmin,
+			TenantID: &ownerTenantID,
+		})
+		return c.Next()
+	})
+	app.Post("/api/v1/dev/clients", h.CreateClient)
+
+	body, _ := json.Marshal(map[string]any{
+		"id":           "client-tenant",
+		"name":         "Tenant Client",
+		"type":         "pkce",
+		"redirectUris": []string{"https://rp.example.com/cb"},
+		"metadata": map[string]any{
+			"tenant_access_restricted": true,
+			"allowed_tenants":          []string{"tenant-b", "tenant-a", "tenant-b"},
+		},
+	})
+	req := httptest.NewRequest(http.MethodPost, "/api/v1/dev/clients", bytes.NewReader(body))
+	req.Header.Set("Content-Type", "application/json")
+
+	resp, err := app.Test(req, -1)
+	assert.NoError(t, err)
+	assert.Equal(t, http.StatusCreated, resp.StatusCode)
+	assert.True(t, clientTenantAccessRestricted(captured.Metadata))
+	assert.Equal(t, []string{"tenant-a", "tenant-b", "tenant-owner"}, clientAllowedTenants(captured.Metadata))
+}
+
+func TestCreateClient_RejectsTenantAccessWithoutAllowedTenants(t *testing.T) {
+	hydraCalled := false
+	transport := roundTripFunc(func(r *http.Request) (*http.Response, error) {
+		if r.Method == http.MethodPost && r.URL.Path == "/clients" {
+			hydraCalled = true
+		}
+		return httpJSONAny(r, http.StatusNotFound, nil), nil
+	})
+
+	h := &DevHandler{
+		Hydra: &service.HydraAdminService{
+			AdminURL:   "http://hydra.test",
+			HTTPClient: &http.Client{Transport: transport},
+		},
+		Keto: new(devMockKetoService),
+	}
+
+	app := fiber.New()
+	app.Use(func(c *fiber.Ctx) error {
+		c.Locals("user_profile", &domain.UserProfileResponse{ID: "user-1", Role: domain.RoleSuperAdmin})
+		return c.Next()
+	})
+	app.Post("/api/v1/dev/clients", h.CreateClient)
+
+	body, _ := json.Marshal(map[string]any{
+		"id":           "client-tenant",
+		"name":         "Tenant Client",
+		"type":         "pkce",
+		"redirectUris": []string{"https://rp.example.com/cb"},
+		"metadata": map[string]any{
+			"tenant_access_restricted": true,
+		},
+	})
+	req := httptest.NewRequest(http.MethodPost, "/api/v1/dev/clients", bytes.NewReader(body))
+	req.Header.Set("Content-Type", "application/json")
+
+	resp, err := app.Test(req, -1)
+	assert.NoError(t, err)
+	assert.Equal(t, http.StatusBadRequest, resp.StatusCode)
+	assert.False(t, hydraCalled)
+}
+
+func TestGetConsentRequest_DeniesTenantAccess(t *testing.T) {
+	transport := roundTripFunc(func(r *http.Request) (*http.Response, error) {
+		switch {
+		case r.URL.Path == "/oauth2/auth/requests/consent" && r.URL.Query().Get("consent_challenge") == "challenge-tenant":
+			return httpJSONAny(r, http.StatusOK, map[string]any{
+				"challenge":       "challenge-tenant",
+				"requested_scope": []string{"openid", "profile"},
+				"skip":            false,
+				"subject":         "user-123",
+				"client": map[string]any{
+					"client_id": "client-tenant",
+					"metadata": map[string]any{
+						"tenant_access_restricted": true,
+						"allowed_tenants":          []string{"tenant-b"},
+					},
+				},
+			}), nil
+		case r.URL.Host == "kratos.test" && r.URL.Path == "/sessions/whoami":
+			return httpJSONAny(r, http.StatusOK, map[string]any{
+				"identity": map[string]any{
+					"id": "user-123",
+					"traits": map[string]any{
+						"email":     "user@test.com",
+						"tenant_id": "tenant-a",
+					},
+				},
+			}), nil
+		default:
+			return httpJSONAny(r, http.StatusNotFound, nil), nil
+		}
+	})
+
+	client := &http.Client{Transport: transport}
+	origDefault := http.DefaultClient
+	http.DefaultClient = client
+	defer func() { http.DefaultClient = origDefault }()
+
+	t.Setenv("KRATOS_PUBLIC_URL", "http://kratos.test")
+
+	h := &AuthHandler{
+		Hydra: &service.HydraAdminService{
+			AdminURL:   "http://hydra.test",
+			HTTPClient: client,
+		},
+	}
+
+	app := fiber.New()
+	tenantID := "tenant-a"
+	app.Use(func(c *fiber.Ctx) error {
+		c.Locals("user_profile", &domain.UserProfileResponse{
+			ID:       "user-123",
+			Role:     domain.RoleUser,
+			TenantID: &tenantID,
+		})
+		return c.Next()
+	})
+	app.Get("/api/v1/auth/consent", h.GetConsentRequest)
+
+	req := httptest.NewRequest(http.MethodGet, "/api/v1/auth/consent?consent_challenge=challenge-tenant", nil)
+	req.Header.Set("Cookie", "ory_kratos_session=session-1")
+
+	resp, err := app.Test(req)
+	assert.NoError(t, err)
+	assert.Equal(t, http.StatusForbidden, resp.StatusCode)
+
+	bodyBytes, _ := io.ReadAll(resp.Body)
+	var body map[string]any
+	assert.NoError(t, json.Unmarshal(bodyBytes, &body))
+	assert.Equal(t, "tenant_not_allowed", body["code"])
+}
+
+func TestAcceptOidcLoginRequest_DeniesTenantAccess(t *testing.T) {
+	transport := roundTripFunc(func(r *http.Request) (*http.Response, error) {
+		switch {
+		case r.URL.Path == "/oauth2/auth/requests/login" && r.URL.Query().Get("login_challenge") == "login-tenant":
+			return httpJSONAny(r, http.StatusOK, map[string]any{
+				"challenge": "login-tenant",
+				"subject":   "user-123",
+				"client": map[string]any{
+					"client_id": "client-tenant",
+					"metadata": map[string]any{
+						"tenant_access_restricted": true,
+						"allowed_tenants":          []string{"tenant-b"},
+					},
+				},
+			}), nil
+		case r.URL.Host == "kratos.test" && r.URL.Path == "/sessions/whoami":
+			return httpJSONAny(r, http.StatusOK, map[string]any{
+				"identity": map[string]any{
+					"id": "user-123",
+					"traits": map[string]any{
+						"email":     "user@test.com",
+						"tenant_id": "tenant-a",
+					},
+				},
+			}), nil
+		default:
+			return httpJSONAny(r, http.StatusNotFound, nil), nil
+		}
+	})
+
+	client := &http.Client{Transport: transport}
+	origDefault := http.DefaultClient
+	http.DefaultClient = client
+	defer func() { http.DefaultClient = origDefault }()
+
+	t.Setenv("KRATOS_PUBLIC_URL", "http://kratos.test")
+
+	h := &AuthHandler{
+		Hydra: &service.HydraAdminService{
+			AdminURL:   "http://hydra.test",
+			HTTPClient: client,
+		},
+	}
+
+	app := fiber.New()
+	tenantID := "tenant-a"
+	app.Use(func(c *fiber.Ctx) error {
+		c.Locals("user_profile", &domain.UserProfileResponse{
+			ID:       "user-123",
+			Role:     domain.RoleUser,
+			TenantID: &tenantID,
+		})
+		return c.Next()
+	})
+	app.Post("/api/v1/auth/oidc/login/accept", h.AcceptOidcLoginRequest)
+
+	reqBody, _ := json.Marshal(map[string]any{
+		"login_challenge": "login-tenant",
+	})
+	req := httptest.NewRequest(http.MethodPost, "/api/v1/auth/oidc/login/accept", bytes.NewReader(reqBody))
+	req.Header.Set("Content-Type", "application/json")
+	req.Header.Set("Cookie", "ory_kratos_session=session-1")
+
+	resp, err := app.Test(req)
+	assert.NoError(t, err)
+	assert.Equal(t, http.StatusForbidden, resp.StatusCode)
+
+	bodyBytes, _ := io.ReadAll(resp.Body)
+	var body map[string]any
+	assert.NoError(t, json.Unmarshal(bodyBytes, &body))
+	assert.Equal(t, "tenant_not_allowed", body["code"])
+}
diff --git a/backend/internal/handler/dev_handler.go b/backend/internal/handler/dev_handler.go
index 1a0b8a95..cc18a86c 100644
--- a/backend/internal/handler/dev_handler.go
+++ b/backend/internal/handler/dev_handler.go
@@ -1528,6 +1528,11 @@ func (h *DevHandler) CreateClient(c *fiber.Ctx) error {
 	}
 	metadata["status"] = status
 	metadata["created_at"] = time.Now().Format(time.RFC3339)
+	var err error
+	metadata, err = normalizeClientTenantAccessMetadata(metadata)
+	if err != nil {
+		return errorJSON(c, fiber.StatusBadRequest, err.Error())
+	}
 
 	tokenAuthMethod := strings.TrimSpace(valueOr(req.TokenEndpointAuthMethod, ""))
 	if tokenAuthMethod == "" {
@@ -1716,6 +1721,10 @@ func (h *DevHandler) UpdateClient(c *fiber.Ctx) error {
 		}
 		metadata["status"] = status
 	}
+	metadata, err = normalizeClientTenantAccessMetadata(metadata)
+	if err != nil {
+		return errorJSON(c, fiber.StatusBadRequest, err.Error())
+	}
 	resolvedClientType := currentSummary.Type
 	if clientType != "" {
 		resolvedClientType = clientType