diff --git a/src/app/core/services/cart/cart.interface.ts b/src/app/core/services/cart/cart.interface.ts
new file mode 100644
index 0000000..d4916aa
--- /dev/null
+++ b/src/app/core/services/cart/cart.interface.ts
@@ -0,0 +1,21 @@
+export interface CartItemProduct {
+  nombre: string;
+  imagen: string | null;
+}
+
+export interface CartItem {
+  id: number;
+  cantidad: number;
+  precio_unitario: string;
+  product_id: number;
+  product_variant_id: number;
+  product: CartItemProduct | null;
+}
+
+export interface Cart {
+  id: number | null;
+  tenant_codigo: string;
+  status: string;
+  items: CartItem[];
+  subtotal: string;
+}
diff --git a/src/app/core/services/cart/cart.service.spec.ts b/src/app/core/services/cart/cart.service.spec.ts
new file mode 100644
index 0000000..ef040ea
--- /dev/null
+++ b/src/app/core/services/cart/cart.service.spec.ts
@@ -0,0 +1,125 @@
+import { TestBed } from '@angular/core/testing';
+import { HttpTestingController, provideHttpClientTesting } from '@angular/common/http/testing';
+import { provideHttpClient } from '@angular/common/http';
+import { describe, it, expect, beforeEach, afterEach, vi } from 'vitest';
+
+import { CartService } from './cart.service';
+import { TenantService } from '../tenant.service';
+import { Cart } from './cart.interface';
+
+describe('CartService', () => {
+  let service: CartService;
+  let httpMock: HttpTestingController;
+  let tenantServiceMock: any;
+
+  const mockCart: Cart = {
+    id: 123,
+    tenant_codigo: 'acme',
+    status: 'active',
+    items: [
+      {
+        id: 1,
+        cantidad: 2,
+        precio_unitario: '10.00',
+        product_id: 5,
+        product_variant_id: 10,
+        product: {
+          nombre: 'Test Product (Size: M)',
+          imagen: null
+        }
+      }
+    ],
+    subtotal: '20.00'
+  };
+
+  beforeEach(() => {
+    tenantServiceMock = {
+      getTenantApiUrl: vi.fn().mockReturnValue('http://api.test/tenants/acme')
+    };
+
+    TestBed.configureTestingModule({
+      providers: [
+        CartService,
+        provideHttpClient(),
+        provideHttpClientTesting(),
+        { provide: TenantService, useValue: tenantServiceMock }
+      ]
+    });
+
+    service = TestBed.inject(CartService);
+    httpMock = TestBed.inject(HttpTestingController);
+  });
+
+  afterEach(() => {
+    httpMock.verify();
+  });
+
+  it('should be created', () => {
+    expect(service).toBeTruthy();
+  });
+
+  it('should initialize with null cart signal', () => {
+    expect(service.cart()).toBeNull();
+  });
+
+  it('should load cart and update signal', () => {
+    service.loadCart().subscribe((cart) => {
+      expect(cart).toEqual(mockCart);
+      expect(service.cart()).toEqual(mockCart);
+    });
+
+    const req = httpMock.expectOne('http://api.test/tenants/acme/cart');
+    expect(req.request.method).toBe('GET');
+    expect(req.request.withCredentials).toBe(true);
+    req.flush({ data: mockCart });
+  });
+
+  it('should add item and update signal', () => {
+    service.addItem(10, 2).subscribe((cart) => {
+      expect(cart).toEqual(mockCart);
+      expect(service.cart()).toEqual(mockCart);
+    });
+
+    const req = httpMock.expectOne('http://api.test/tenants/acme/cart/items');
+    expect(req.request.method).toBe('POST');
+    expect(req.request.body).toEqual({ product_variant_id: 10, cantidad: 2 });
+    expect(req.request.withCredentials).toBe(true);
+    req.flush({ data: mockCart });
+  });
+
+  it('should update item quantity and update signal', () => {
+    const updatedCart = { ...mockCart, subtotal: '30.00' };
+    updatedCart.items[0].cantidad = 3;
+
+    service.updateItemQuantity(10, 3).subscribe((cart) => {
+      expect(cart).toEqual(updatedCart);
+      expect(service.cart()).toEqual(updatedCart);
+    });
+
+    const req = httpMock.expectOne('http://api.test/tenants/acme/cart/items/10');
+    expect(req.request.method).toBe('PATCH');
+    expect(req.request.body).toEqual({ cantidad: 3 });
+    expect(req.request.withCredentials).toBe(true);
+    req.flush({ data: updatedCart });
+  });
+
+  it('should remove item and update signal', () => {
+    const emptyCart: Cart = {
+      id: 123,
+      tenant_codigo: 'acme',
+      status: 'active',
+      items: [],
+      subtotal: '0.00'
+    };
+
+    service.removeItem(10).subscribe((cart) => {
+      expect(cart).toEqual(emptyCart);
+      expect(service.cart()).toEqual(emptyCart);
+    });
+
+    const req = httpMock.expectOne('http://api.test/tenants/acme/cart/items/10');
+    expect(req.request.method).toBe('DELETE');
+    expect(req.request.withCredentials).toBe(true);
+    req.flush({ data: emptyCart });
+  });
+});
diff --git a/src/app/core/services/cart/cart.service.ts b/src/app/core/services/cart/cart.service.ts
new file mode 100644
index 0000000..16c3f20
--- /dev/null
+++ b/src/app/core/services/cart/cart.service.ts
@@ -0,0 +1,71 @@
+import { inject, Injectable, signal } from '@angular/core';
+import { HttpClient } from '@angular/common/http';
+import { map, Observable, tap } from 'rxjs';
+
+import { ApiResponse } from '../api-response.interface';
+import { TenantService } from '../tenant.service';
+import { Cart } from './cart.interface';
+
+@Injectable({
+  providedIn: 'root'
+})
+export class CartService {
+  private readonly http = inject(HttpClient);
+  private readonly tenantService = inject(TenantService);
+
+  private readonly cartState = signal<Cart | null>(null);
+  readonly cart = this.cartState.asReadonly();
+
+  private get tenantApiUrl(): string {
+    return this.tenantService.getTenantApiUrl();
+  }
+
+  loadCart(): Observable<Cart> {
+    return this.http
+      .get<ApiResponse<Cart>>(`${this.tenantApiUrl}/cart`, {
+        withCredentials: true
+      })
+      .pipe(
+        map((response) => response.data),
+        tap((cart) => this.cartState.set(cart))
+      );
+  }
+
+  addItem(productVariantId: number, cantidad: number): Observable<Cart> {
+    return this.http
+      .post<ApiResponse<Cart>>(
+        `${this.tenantApiUrl}/cart/items`,
+        { product_variant_id: productVariantId, cantidad },
+        { withCredentials: true }
+      )
+      .pipe(
+        map((response) => response.data),
+        tap((cart) => this.cartState.set(cart))
+      );
+  }
+
+  updateItemQuantity(productVariantId: number, cantidad: number): Observable<Cart> {
+    return this.http
+      .patch<ApiResponse<Cart>>(
+        `${this.tenantApiUrl}/cart/items/${productVariantId}`,
+        { cantidad },
+        { withCredentials: true }
+      )
+      .pipe(
+        map((response) => response.data),
+        tap((cart) => this.cartState.set(cart))
+      );
+  }
+
+  removeItem(productVariantId: number): Observable<Cart> {
+    return this.http
+      .delete<ApiResponse<Cart>>(
+        `${this.tenantApiUrl}/cart/items/${productVariantId}`,
+        { withCredentials: true }
+      )
+      .pipe(
+        map((response) => response.data),
+        tap((cart) => this.cartState.set(cart))
+      );
+  }
+}