The 16-year-old has officially agreed terms with the Premier League club.
Adjei, who plays as a forward, will now be integrated into United’s youth setup.
This was revealed by football transfer expert, Fabrizio Romano, via his X page on Saturday.
Romano also noted that the necessary documents will be approved next week.
He wrote: “Manchester United complete deal to sign Tyler Adjei from Reading — all done for 16 year old to join #mufc project.
“Talented forward has accepted all terms, deal in place — as @AndyMitten reported.
