Williams agreed to a two-way contract with the Celtics on Monday, John Karalis of BostonSportsJournal.com reports.
Williams signed a two-way deal with Boston ahead of his rookie season before being upgraded to a standard contract. The 24-year-old center appeared in 22 regular-season games (two starts) in 2025-26, averaging 1.4 points and 1.8 rebounds in 6.6 minutes per contest. He will likely spend most of his time with the G League's Maine Celtics and will have to compete for playing time with Chris Cenac and Luka Garza behind Neemias Queta with the parent club.