Defender extends stay at Newcastle
The club has taken up an option to extend the 21-year-old's deal, which had been due to expire this summer, by two more years.
Mbabu – who joined Newcastle from Swiss club Servette in January 2013 – made his first-team debut in a Capital One Cup tie against Sheffield Wednesday last season and impressed in three Premier League appearances.
United have also agreed new professional contracts for Macaulay Gillesphey, Liam Smith and Tom Heardman.
Newcastle have also offered deals to teenagers Stefan Broccoli, Kyle Cameron, Liam Gibson, Brendan Pearson and Callum Williams.
Academy players Luke Charman, Jamie Holmes, Jack Hunter, Sean Longstaff, Michael Newberry, Ben Smith, Dan Ward and Paul Woolston have been given extended scholarships.