diff --git a/addons/mrp_subcontracting/models/mrp_production.py b/addons/mrp_subcontracting/models/mrp_production.py
index c311ffb271b3a..652ae81cd0616 100644
--- a/addons/mrp_subcontracting/models/mrp_production.py
+++ b/addons/mrp_subcontracting/models/mrp_production.py
@@ -58,7 +58,15 @@ def write(self, vals):
             unauthorized_fields = set(vals.keys()) - set(self._get_writeable_fields_portal_user())
             if unauthorized_fields:
                 raise AccessError(_("You cannot write on fields %s in mrp.production.", ', '.join(unauthorized_fields)))
-        return super().write(vals)
+        res = super().write(vals)
+        if 'lot_producing_id' in vals and vals.get('lot_producing_id'):
+            for production in self:
+                if production._should_auto_record_subcontract_components():
+                    try:
+                        production.subcontracting_record_component()
+                    except Exception:
+                        pass
+        return res
 
     def action_merge(self):
         if any(production._get_subcontract_move() for production in self):
@@ -204,3 +212,26 @@ def _subcontract_sanity_check(self):
                 if sml.tracking != 'none' and not sml.lot_id:
                     raise UserError(_('You must enter a serial number for each line of %s') % sml.product_id.display_name)
         return True
+
+    def action_generate_serial(self):
+        res = super().action_generate_serial()
+        if self._should_auto_record_subcontract_components():
+            try:
+                self.subcontracting_record_component()
+            except Exception:
+                pass
+        return res
+
+    def _should_auto_record_subcontract_components(self):
+        self.ensure_one()
+        if (
+            not self.lot_producing_id
+            or self.subcontracting_has_been_recorded
+            or not self._get_subcontract_move()
+            or self.state in ('done', 'cancel')
+            or self.product_id.tracking != 'serial'
+        ):
+            return False
+        if not self.move_raw_ids or not any(self.move_raw_ids.mapped('quantity_done')):
+            return False
+        return True
diff --git a/addons/mrp_subcontracting/tests/test_subcontracting.py b/addons/mrp_subcontracting/tests/test_subcontracting.py
index 458eb113a5b03..49b761a37995c 100644
--- a/addons/mrp_subcontracting/tests/test_subcontracting.py
+++ b/addons/mrp_subcontracting/tests/test_subcontracting.py
@@ -1880,3 +1880,70 @@ def test_bom_subcontracting_product_dynamic_attribute(self):
         })
         report_values = self.env['report.mrp.report_bom_structure']._get_report_data(bom_id=bom.id, searchVariant=False)
         self.assertTrue(report_values)
+
+    def test_subcontracting_serial_mass_produce(self):
+        """
+        Test that Mass Produce on a subcontracting MO with serial-tracked finished
+        products properly records subcontracted components and syncs serials to receipt.
+        """
+        # Set finished product to serial tracking
+        self.finished.tracking = 'serial'
+
+        # Get subcontract location
+        subcontract_location = self.subcontractor_partner1.property_stock_subcontractor
+
+        # Create a receipt picking from the subcontractor
+        picking_form = Form(self.env['stock.picking'])
+        picking_form.picking_type_id = self.env.ref('stock.picking_type_in')
+        picking_form.partner_id = self.subcontractor_partner1
+        with picking_form.move_ids_without_package.new() as move:
+            move.product_id = self.finished
+            move.product_uom_qty = 2
+        receipt = picking_form.save()
+        receipt.action_confirm()
+
+        # Add components to subcontractor location
+        self.env['stock.quant']._update_available_quantity(
+            self.comp1, subcontract_location, 2
+        )
+        self.env['stock.quant']._update_available_quantity(
+            self.comp2, subcontract_location, 2
+        )
+
+        # Get the created manufacturing order
+        production = receipt.move_ids.move_orig_ids.production_id
+        production.action_assign()
+
+        # Use Mass Produce wizard to assign serial numbers
+        action = production.action_serial_mass_produce_wizard()
+        wizard = Form(self.env['stock.assign.serial'].with_context(**action['context']))
+        wizard.next_serial_number = 'SN0001'
+        wizard.next_serial_count = 2
+        action = wizard.save().generate_serial_numbers_production()
+        wizard = Form(self.env['stock.assign.serial'].browse(action['res_id']))
+        wizard.save().apply()
+
+        # Get all productions after split
+        productions = receipt.move_ids.move_orig_ids.production_id.sorted('id')
+
+        # Verify: should have 2 productions (one per serial)
+        self.assertEqual(len(productions), 2)
+
+        # Verify: subcontracting_has_been_recorded should be True for both
+        self.assertEqual(
+            productions.mapped('subcontracting_has_been_recorded'), [True, True],
+            "Mass Produce should have recorded subcontracted components for both MOs"
+        )
+
+        # Verify: serials are assigned to productions
+        self.assertEqual(
+            productions.mapped('lot_producing_id.name'), ['SN0001', 'SN0002'],
+            "Serial numbers should be assigned to split productions"
+        )
+
+        # Verify: serials are synced to receipt move lines
+        self.assertEqual(
+            sorted(receipt.move_line_ids.mapped('lot_id.name')),
+            ['SN0001', 'SN0002'],
+            "Serial numbers should be synced to receipt move lines"
+        )
diff --git a/addons/mrp_subcontracting/wizard/__init__.py b/addons/mrp_subcontracting/wizard/__init__.py
index 0594ad02b2a1b..3b45e10da68d8 100644
--- a/addons/mrp_subcontracting/wizard/__init__.py
+++ b/addons/mrp_subcontracting/wizard/__init__.py
@@ -4,3 +4,4 @@
 from . import stock_picking_return
 from . import mrp_consumption_warning
 from . import change_production_qty
+from . import stock_assign_serial_numbers
diff --git a/addons/mrp_subcontracting/wizard/stock_assign_serial_numbers.py b/addons/mrp_subcontracting/wizard/stock_assign_serial_numbers.py
new file mode 100644
index 0000000000000..a739e09f8b95d
--- /dev/null
+++ b/addons/mrp_subcontracting/wizard/stock_assign_serial_numbers.py
@@ -0,0 +1,30 @@
+# -*- coding: utf-8 -*-
+# Part of Odoo. See LICENSE file for full copyright and licensing details.
+
+from odoo import models
+
+
+class StockAssignSerialNumbers(models.TransientModel):
+    _inherit = 'stock.assign.serial'
+
+    def _assign_serial_numbers(self, cancel_remaining_quantity=False):
+        serial_numbers = set(self._get_serial_numbers())
+        res = super()._assign_serial_numbers(cancel_remaining_quantity)
+        if not serial_numbers:
+            return res
+        # Record subcontracted components for each production with assigned serial
+        # When Mass Produce splits a subcontracting MO and assigns serials,
+        # subcontracting_record_component() is not called automatically,
+        # causing finished serials to not sync to receipt move lines
+        productions = (
+            self.production_id.procurement_group_id.mrp_production_ids.filtered(
+                lambda mo: mo.state not in ('done', 'cancel')
+                and not mo.subcontracting_has_been_recorded
+                and mo._get_subcontract_move()
+                and mo.lot_producing_id
+                and mo.lot_producing_id.name in serial_numbers
+            )
+        )
+        for production in productions:
+            production.subcontracting_record_component()
+        return res