The school said it would formally introduce Les at a news conference Friday.
Les' son, Tyler, will be a sophomore at UC Davis this season.
Les was fired in March after nine seasons at Bradley, a run that included an upset of Kansas in the first round of the 2006 NCAA tournament when the Braves reached the regional semifinals.
The Braves were 12-20 overall and 4-14 in the Missouri Valley Conference last season.
Les played four of his seven NBA seasons with the Sacramento Kings. He was as an assistant coach with the Sacramento Monarchs of the WNBA.
He had a 154-140 record at Bradley.
The Aggies went 10-20 and 4-12 in the Big West last season.