The deal has been rumoured for most of the summer, but the player has now completed a medical and is expected to be unveiled officially this afternoon, according to a report from Sky Sports News and the player's own Twitter account.
"Professional footballer at Manchester United Football Club. Views are my own, not those of @ManUtd," Shaw's new Twitter profile says.
The deal for the 18-year-old is thought to be for five years and worth around £100,000 per week. He joins the club a day after United officially announced the signing of Ander Herrera from Athletic Bilbao.