It was earlier reported the teenage midfielder had already joined the Red Devils. According to Goal.com, a deal for Traore was only completed last week as he will start his United career with their youth setup.
The youngster came up through the ranks of Paris Saint-Germain's youth setup, before leaving the Ligue 1 giants in August 2016. He feared that continuing at Parc des Princes would reduce his chances of breaking into their first team.
Traore spent the last season with amateur side Sarcelles and has recently attracted interest top European clubs. Apart from United, their local rivals City and the Champions League runners-up Juventus were also looking at the option of signing him.
Juventus were hoping to convince the player to snub advances from the Red Devils and join the Old Lady. However, Traore has rejected advances from other clubs in order to join the 20-time English champions.
The same report also claims the midfielder, who will turn 17 in January, will sign a four-year deal at United. It is unlikely that he will get a shot in Jose Mourinho's first team as Traore will have to come up through the Red Devils' academy. He has featured for France Under-16s and was the only player in the national set up who was not with a professional club.
The former PSG youngster will follow Arsenal fan Ethan Galbraith to their academy. The Northern Ireland midfielder will travel to United and sign a three-year deal, having already agreed to a pre-contract in January.
Meanwhile, United are without a manager for their Under-23 side. Warren Joyce left the position last November and the club's head of the academy and former midfielder Nicky Butt took over United Under-23s on a temporary basis.
According to ESPN, former Sunderland manager Ricky Sbragia could be appointed as Joyce's successor. The 61-year-old is without a job since leaving the position of Scotland Under-21s last September and is expected to be appointed as the Red Devils new Under-23 manager.