Mathieu, 24, tore his right ACL last December and his LCL and left ACL in December 2013. When healthy, he has been one of the league’s most versatile defensive backs.
The Cardinals reportedly expect him to return to practice in two weeks.
Mathieu recorded 89 tackles and five interceptions last season, primarily playing safety but also taking snaps at cornerback.
Mathieu appeared to confirm the news on Twitter.