diff --git a/app/controllers/api/v1/payment_providers/stripe_connect_controller.rb b/app/controllers/api/v1/payment_providers/stripe_connect_controller.rb
new file mode 100644
index 000000000000..13c98fa00139
--- /dev/null
+++ b/app/controllers/api/v1/payment_providers/stripe_connect_controller.rb
@@ -0,0 +1,44 @@
+# frozen_string_literal: true
+
+module Api
+  module V1
+    module PaymentProviders
+      # Registers a reseller's Stripe Connect account (acct_…) as an
+      # entity-scoped Stripe payment provider, so the agency's sub-account
+      # retail invoices collect on the agency's OWN connected account.
+      #
+      # Server-to-server (api_key auth). The connected provider reuses the
+      # organization's platform Stripe key — calls run on the connected account
+      # via the Stripe-Account header (see PaymentProviders::StripeProvider).
+      # Idempotent by provider code.
+      class StripeConnectController < Api::BaseController
+        def create
+          platform_provider = current_organization.stripe_payment_providers
+            .where(billing_entity_id: nil).first
+          return not_found_error(resource: "stripe_payment_provider") if platform_provider.blank?
+
+          result = ::PaymentProviders::StripeService.new.create_or_update(
+            organization_id: current_organization.id,
+            code: create_params[:code],
+            name: create_params[:name],
+            secret_key: platform_provider.secret_key,
+            billing_entity_code: create_params[:billing_entity_code],
+            connected_account_id: create_params[:connected_account_id]
+          )
+
+          if result.success?
+            render(json: {payment_provider: {lago_id: result.stripe_provider.id, code: result.stripe_provider.code}})
+          else
+            render_error_response(result)
+          end
+        end
+
+        private
+
+        def create_params
+          params.require(:payment_provider).permit(:code, :name, :billing_entity_code, :connected_account_id)
+        end
+      end
+    end
+  end
+end
diff --git a/config/routes.rb b/config/routes.rb
index 57f43f1b2e3c..631545794f99 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -54,6 +54,9 @@
 
       resources :billing_entities, param: :code, only: %i[index show update create]
 
+      # Register a reseller's Stripe Connect account as an entity-scoped provider.
+      post "payment_providers/stripe_connect", to: "payment_providers/stripe_connect#create"
+
       resources :customers, param: :external_id, only: %i[create index show destroy] do
         get :portal_url
 
diff --git a/db/migrate/20260728000000_add_billing_entity_to_payment_providers.rb b/db/migrate/20260728000000_add_billing_entity_to_payment_providers.rb
index fe3901389b44..33929aa363ff 100644
--- a/db/migrate/20260728000000_add_billing_entity_to_payment_providers.rb
+++ b/db/migrate/20260728000000_add_billing_entity_to_payment_providers.rb
@@ -5,12 +5,13 @@
 # for that entity's customers. NULL keeps the existing organization-level
 # behaviour unchanged (all existing providers stay org-level).
 class AddBillingEntityToPaymentProviders < ActiveRecord::Migration[8.0]
+  disable_ddl_transaction!
+
   def change
-    add_reference :payment_providers,
-      :billing_entity,
-      type: :uuid,
-      null: true,
-      foreign_key: true,
-      index: true
+    # Column + index only (no DB-level FK): billing_entity_id is an optional,
+    # app-managed reference; keeping it FK-free avoids the schema-dump churn and
+    # keeps the change minimal.
+    add_reference :payment_providers, :billing_entity, type: :uuid, null: true,
+      index: {algorithm: :concurrently}
   end
 end
diff --git a/db/structure.sql b/db/structure.sql
index 92706cfc6dd0..326c78108813 100644
--- a/db/structure.sql
+++ b/db/structure.sql
@@ -250,7 +250,6 @@ ALTER TABLE IF EXISTS ONLY public.wallets DROP CONSTRAINT IF EXISTS fk_rails_2b3
 ALTER TABLE IF EXISTS ONLY public.usage_thresholds DROP CONSTRAINT IF EXISTS fk_rails_2908dd8de5;
 ALTER TABLE IF EXISTS ONLY public.wallets DROP CONSTRAINT IF EXISTS fk_rails_28077d4aa2;
 ALTER TABLE IF EXISTS ONLY public.charge_filters DROP CONSTRAINT IF EXISTS fk_rails_27b55b8574;
-ALTER TABLE IF EXISTS ONLY public.payment_providers DROP CONSTRAINT IF EXISTS fk_rails_pp_billing_entity;
 ALTER TABLE IF EXISTS ONLY public.payment_providers DROP CONSTRAINT IF EXISTS fk_rails_26be2f764d;
 ALTER TABLE IF EXISTS ONLY public.billing_entities_taxes DROP CONSTRAINT IF EXISTS fk_rails_268c288aaa;
 ALTER TABLE IF EXISTS ONLY public.fees DROP CONSTRAINT IF EXISTS fk_rails_257af22645;
@@ -10290,14 +10289,6 @@ ALTER TABLE ONLY public.payment_providers
     ADD CONSTRAINT fk_rails_26be2f764d FOREIGN KEY (organization_id) REFERENCES public.organizations(id);
 
 
---
--- Name: payment_providers fk_rails_pp_billing_entity; Type: FK CONSTRAINT; Schema: public; Owner: -
---
-
-ALTER TABLE ONLY public.payment_providers
-    ADD CONSTRAINT fk_rails_pp_billing_entity FOREIGN KEY (billing_entity_id) REFERENCES public.billing_entities(id);
-
-
 --
 -- Name: charge_filters fk_rails_27b55b8574; Type: FK CONSTRAINT; Schema: public; Owner: -
 --
diff --git a/spec/requests/api/v1/payment_providers/stripe_connect_controller_spec.rb b/spec/requests/api/v1/payment_providers/stripe_connect_controller_spec.rb
new file mode 100644
index 000000000000..2f6ed31fe6b1
--- /dev/null
+++ b/spec/requests/api/v1/payment_providers/stripe_connect_controller_spec.rb
@@ -0,0 +1,78 @@
+# frozen_string_literal: true
+
+require "rails_helper"
+
+RSpec.describe Api::V1::PaymentProviders::StripeConnectController do
+  let(:organization) { create(:organization) }
+  let(:billing_entity) { create(:billing_entity, organization:) }
+  let(:platform_provider) { create(:stripe_provider, organization:) }
+
+  describe "POST /api/v1/payment_providers/stripe_connect" do
+    subject { post_with_token(organization, "/api/v1/payment_providers/stripe_connect", params) }
+
+    let(:params) do
+      {
+        payment_provider: {
+          code: "stripe_reseller_abc",
+          name: "Acme Agency (Stripe)",
+          billing_entity_code: billing_entity.code,
+          connected_account_id: "acct_123"
+        }
+      }
+    end
+
+    before do
+      billing_entity
+      platform_provider
+    end
+
+    it "creates an entity-scoped connected Stripe provider on the platform key" do
+      expect { subject }.to change(PaymentProviders::StripeProvider, :count).by(1)
+      expect(response).to be_successful
+
+      provider = PaymentProviders::StripeProvider.find_by(code: "stripe_reseller_abc")
+      expect(provider).to be_present
+      expect(provider.connected_account_id).to eq("acct_123")
+      expect(provider.billing_entity_id).to eq(billing_entity.id)
+      # Reuses the org's platform Stripe key (no secret is sent over the wire).
+      expect(provider.secret_key).to eq(platform_provider.secret_key)
+      expect(json[:payment_provider][:code]).to eq("stripe_reseller_abc")
+    end
+
+    it "produces connected request options that carry the Stripe-Account header" do
+      subject
+      provider = PaymentProviders::StripeProvider.find_by(code: "stripe_reseller_abc")
+      expect(provider.stripe_request_options).to eq(
+        api_key: platform_provider.secret_key,
+        stripe_account: "acct_123"
+      )
+    end
+
+    context "when the organization has no platform Stripe provider" do
+      let(:platform_provider) { nil }
+
+      it "returns not found" do
+        subject
+        expect(response).to have_http_status(:not_found)
+      end
+    end
+
+    context "when the billing entity code is unknown" do
+      let(:params) do
+        {
+          payment_provider: {
+            code: "stripe_reseller_x",
+            name: "x",
+            billing_entity_code: "does-not-exist",
+            connected_account_id: "acct_1"
+          }
+        }
+      end
+
+      it "does not create a provider and fails" do
+        expect { subject }.not_to change(PaymentProviders::StripeProvider, :count)
+        expect(response).not_to be_successful
+      end
+    end
+  end
+end