Stewart chose the Huskies over Duke, Michigan State, Syracuse and Kentucky during an announcement on ESPN.
He took official visits to all five of his finalists during the fall but decided not to commit during the early signing period. Washington head coach Mike Hopkins had a relationship with Stewart from his time as an assistant coach at Syracuse and continued to recruit the big man once he took over at Washington in March 2017.
"Me and Coach Hopkins go way back," Stewart said. "Once he got that head-coaching job at Washington, it changed a lot. At first, I wasn't leaning toward them, but as me and Coach Hopkins continued to talk, he's the type of guy that's like me -- different, works hard and wants to start his own legacy -- and that's what I want to do. I'm not an average or normal recruit. I could've went to another school and just been another one of those guys. I feel like I'm special, and I feel like I deserve to go out there. I feel like they deserve a top recruit. It's been a while."
Although the perceived favorite in his recruitment changed several times over the summer and fall -- from Duke to Villanova to Kentucky to Michigan State -- the Huskies remained a factor due to Stewart's connection with Hopkins. Washington already had two players from Stewart's grassroots program on the roster, guard Nahziah Carter and forward Hameir Wright.
"I'm a relationship guy," Stewart said. "At the end of the day, the head coach calls the shots. For me to have that type of relationship with the head coach, it was special."
A 6-foot-9 center from Rochester, New York, who plays at La Lumiere School (Indiana), Stewart ranks No. 5 in the ESPN 100.
He is one of the most consistent performers in the 2019 class. He averaged 18.0 points and 11.1 rebounds for the Albany City Rocks on the Nike EYBL circuit last spring and summer, while shooting 57.0 percent from the field. Stewart held his own against fellow five-star big men, going for 19 points and six rebounds against No. 1 prospect James Wiseman, and 24 points and 13 rebounds against North Carolina signee Armando Bacot.
Stewart also won a gold medal last summer for USA Basketball with the under-17 World Cup team, averaging 11.1 points and 8.4 rebounds in Argentina.
This is Hopkins' second significant pickup in the last several weeks, as Washington also landed Kentucky transfer Quade Green in December. Stewart and Green will enter the fold next season with a pair of four-star guards, RaeQuan Battle and Marcus Tsohonis. The Huskies are also still heavily involved with uncommitted top-10 prospect Jaden McDaniels, who took an official visit to campus in October.
"I'm going after Jaden McDaniels now, and we're trying to build something out there," Stewart said. "If we get him, man, game-changer."