The deal was first reported by Sam Amick and Jeff Zillgitt of USA Today. Financial terms and length of the contract were not disclosed.
Wiggins was the No. 1 selection by the Cavaliers in last month's draft and joins other NBA stars such as Tim Duncan, Dwight Howard, Derrick Rose, John Wall, Damian Lillard and Joakim Noah who endorse Adidas.
MORE NBA COVERAGE: NBA free agency: Latest buzz, rumors | Ranking the NBA's top 25 free agents | Ten bargain buys in NBA free agency | NBA free agency: Early market trends | NBA free agency: Grading every deal
Wiggins averaged 17.1 points, 5.9 rebounds, 1.5 assists per game in his one and only season at Kansas.