diff --git a/erpnext/accounts/doctype/sales_invoice/sales_invoice.py b/erpnext/accounts/doctype/sales_invoice/sales_invoice.py
index ff81a114d54..b3ef8e23985 100644
--- a/erpnext/accounts/doctype/sales_invoice/sales_invoice.py
+++ b/erpnext/accounts/doctype/sales_invoice/sales_invoice.py
@@ -1556,8 +1556,12 @@ class SalesInvoice(SellingController):
 				)
 
 	def update_project(self):
-		if self.project:
-			project = frappe.get_doc("Project", self.project)
+		unique_projects = list(set([d.project for d in self.get("items") if d.project]))
+		if self.project and self.project not in unique_projects:
+			unique_projects.append(self.project)
+
+		for p in unique_projects:
+			project = frappe.get_doc("Project", p)
 			project.update_billed_amount()
 			project.db_update()
 
diff --git a/erpnext/accounts/doctype/sales_invoice/test_sales_invoice.py b/erpnext/accounts/doctype/sales_invoice/test_sales_invoice.py
index f4b9349c577..6e4c6002016 100644
--- a/erpnext/accounts/doctype/sales_invoice/test_sales_invoice.py
+++ b/erpnext/accounts/doctype/sales_invoice/test_sales_invoice.py
@@ -3842,6 +3842,20 @@ class TestSalesInvoice(FrappeTestCase):
 		self.assertTrue(jv)
 		self.assertEqual(jv[0], si.grand_total)
 
+	def test_total_billed_amount(self):
+		si = create_sales_invoice(do_not_submit=True)
+
+		project = frappe.new_doc("Project")
+		project.project_name = "Test Total Billed Amount"
+		project.save()
+
+		si.project = project.name
+		si.save()
+		si.submit()
+
+		doc = frappe.get_doc("Project", project.name)
+		self.assertEqual(doc.total_billed_amount, si.grand_total)
+
 
 def check_gl_entries(doc, voucher_no, expected_gle, posting_date):
 	gl_entries = frappe.db.sql(