Alexander will rejoin cornerback Trae Waynes, who also left for the Bengals this week on a three-year, $42 million agreement.
Former Houston Texans defensive lineman D.J. Reader has agreed to sign a four-year, $53 million contract with the Cincinnati Bengals, according to Aaron Wilson of the Houston Chronicle. Cornerback Xavier Rhodes was also let go, so he could be an ex-Viking too.
As for the Vikings, Mike Hughes could be in line to replace Alexander in the slot, if needed, or move to one of the starting outside spots.
A second-round pick in the 2016 draft by Minnesota, Alexander had two interceptions, 21 pass breakups, 103 tackles, nine tackles for loss and eight quarterback hits in 55 games and 10 starts.
The cornerback allowed a 90.2 passer rating into his coverage in 2019. He was one of the few starters to play in the Vikings' meaningless regular-season finale against the Bears at U.S. Bank Stadium.
Alexander's relatively affordable deal for Cincinnati, after ranking 10th among National Football League slot defenders allowing an 85.7 passer rating when targeted last season.