It's a one-year, $1.6-million deal, a source told The Athletic's Michael Scotto.
The 24-year-old is a restricted free agent, which gives the Warriors the opportunity to match the T-Wolves' offer. Golden State tendered a $1.8-million qualifying offer to the big man last week.
Bell drew interest from the Houston Rockets, Oklahoma City Thunder, and Utah Jazz but chose Minnesota because he believed the Timberwolves presented the best opportunity for a bigger role, a league source told Mark Medina of the Mercury News.
The Warriors have no plans to match Minnesota's offer sheet for Bell in the hopes of retaining Kevon Looney, adds Medina.
Bell was a part of Golden State's championship squad in 2018 and averaged 3.3 points, 2.7 boards, and 0.8 blocks across 68 appearances this past campaign.