diff --git a/erpnext/manufacturing/doctype/production_plan/production_plan.py b/erpnext/manufacturing/doctype/production_plan/production_plan.py
index 2cdf8d3..66d458b 100644
--- a/erpnext/manufacturing/doctype/production_plan/production_plan.py
+++ b/erpnext/manufacturing/doctype/production_plan/production_plan.py
@@ -656,6 +656,8 @@
 			row.idx = idx + 1
 			self.append("sub_assembly_items", row)
 
+		self.set_default_supplier_for_subcontracting_order()
+
 	def set_sub_assembly_items_based_on_level(self, row, bom_data, manufacturing_type=None):
 		"Modify bom_data, set additional details."
 		for data in bom_data:
@@ -667,6 +669,32 @@
 				"Subcontract" if data.is_sub_contracted_item else "In House"
 			)
 
+	def set_default_supplier_for_subcontracting_order(self):
+		items = [
+			d.production_item for d in self.sub_assembly_items if d.type_of_manufacturing == "Subcontract"
+		]
+
+		if not items:
+			return
+
+		default_supplier = frappe._dict(
+			frappe.get_all(
+				"Item Default",
+				fields=["parent", "default_supplier"],
+				filters={"parent": ("in", items), "default_supplier": ("is", "set")},
+				as_list=1,
+			)
+		)
+
+		if not default_supplier:
+			return
+
+		for row in self.sub_assembly_items:
+			if row.type_of_manufacturing != "Subcontract":
+				continue
+
+			row.supplier = default_supplier.get(row.production_item)
+
 	def combine_subassembly_items(self, sub_assembly_items_store):
 		"Aggregate if same: Item, Warehouse, Inhouse/Outhouse Manu.g, BOM No."
 		key_wise_data = {}
diff --git a/erpnext/manufacturing/doctype/production_plan/test_production_plan.py b/erpnext/manufacturing/doctype/production_plan/test_production_plan.py
index e2415ad..1d2d1bd 100644
--- a/erpnext/manufacturing/doctype/production_plan/test_production_plan.py
+++ b/erpnext/manufacturing/doctype/production_plan/test_production_plan.py
@@ -281,6 +281,31 @@
 		pln.reload()
 		pln.cancel()
 
+	def test_production_plan_subassembly_default_supplier(self):
+		from erpnext.manufacturing.doctype.bom.test_bom import create_nested_bom
+
+		bom_tree_1 = {"Test Laptop": {"Test Motherboard": {"Test Motherboard Wires": {}}}}
+		bom = create_nested_bom(bom_tree_1, prefix="")
+
+		item_doc = frappe.get_doc("Item", "Test Motherboard")
+		company = "_Test Company"
+
+		item_doc.is_sub_contracted_item = 1
+		for row in item_doc.item_defaults:
+			if row.company == company and not row.default_supplier:
+				row.default_supplier = "_Test Supplier"
+
+		if not item_doc.item_defaults:
+			item_doc.append("item_defaults", {"company": company, "default_supplier": "_Test Supplier"})
+
+		item_doc.save()
+
+		plan = create_production_plan(item_code="Test Laptop", use_multi_level_bom=1, do_not_submit=True)
+		plan.get_sub_assembly_items()
+		plan.set_default_supplier_for_subcontracting_order()
+
+		self.assertEqual(plan.sub_assembly_items[0].supplier, "_Test Supplier")
+
 	def test_production_plan_combine_subassembly(self):
 		"""
 		Test combining Sub assembly items belonging to the same BOM in Prod Plan.