Sancho joined Watford at the age of seven. In March 2015 at the age of 14 Sancho moved to Manchester City for an initial fee of £66,000 under the EPPP which could rise to £500,000 with add ons. Sancho continued to impress in the Manchester City academy and was one of a trio of players that the Manchester City chairman, Khaldoon Al Mubarak, said would be fast tracked into the senior set up in May 2017. In July 2017, Sancho was omitted from Manchester City's pre season tour squad due to a dispute over assurances of playing time in a new contract. It was subsequently reported that Sancho was attempting to force a move away from the club.