The NBA made the announcement on Sunday after Powell was selected by a panel of media members.
Powell, six-foot-four 215 pounds, averaged 18.3 points, 4.3 rebounds and 25.5 minutes in four outings. He shot .509 from the field and .444 from three-point range to lead the team in scoring in all four games — including 20 points in Toronto's opener versus Sacramento.
The 22-year-old UCLA product was selected in the second round, 46th overall by Toronto in the 2015 NBA Draft. He averaged 16.4 points, 4.7 rebounds and 1.8 steals in 36 games last season as a senior with the Bruins. He was named first-team All-Pac-12 and an Honourable Mention selection on the All-Pac-12 Defensive Team.
Powell joined Kyle Anderson (San Antonio), Seth Curry (New Orleans), Doug McDermott (Chicago) and T.J. Warren (Phoenix) as members of the All-NBA Summer League 2015 First Team.