The 18-year-old, who initially joined the Seagulls on loan in January, has signed a contract until June 2023 and will continue his development at the club’s under-23s.
The young gun made four Premier League 2 appearances for Albion’s under-23s, without finding the net, last season.
Baker-Boaitey also appeared five times in the Under-18 Premier League, scoring once.
Speaking to the club website, under-23s manager Andrew Crofts said: “Since he came on loan in January, Benicio has shown his ability and worked hard in both training and matches to earn the move.
“We are really looking forward to working with him on his ongoing development this coming season.”