In crunch talks held at Carbis Bay, Cornwall, the EU chief demanded the UK implement the Northern Ireland Protocol in full.
Mr Johnson was confronted two-on-one by Ms von der Leyen and European Council President Charles Michel.
Brexit has dominated most of this morning’s G7 summit, with Mr Johnson holding a number of bilateral meetings with EU leaders.
As well as Ms von der Leyen and Mr Michel, the Prime Minister held talks with France’s Emmanuel Macron followed by Germany’s Angela Merkel.
“The Good Friday Agreement and peace on the island of Ireland are paramount,” Ms von der Leyen said.
“Both sides must implement what we agreed on. There is complete EU unity on this.”
More to follow…