Manziel signed the AAF standard player agreement on Saturday, according to ESPN's Adam Schefter, which will officially allow teams to sign the quarterback.
Manziel was released by the Montreal Alouettes of the Canadian Football League earlier this month.
As of this moment Manziel does not have a team, but he will go through the AAF waiver system since the San Antonio Commanders released his college allocation rights. According to a release from the CFL, Manziel "contravened the agreement which made him eligible to play in the league". The Express lost to the Salt Lake Stallions 22-9 in Week 6, losing quarterback Zach Mettenberger to an apparent ankle injury on their first offensive play.
The 2012 Heisman Trophy victor at Texas A&M had his contract with the CFL terminated this offseason. Mettenberger had replaced Christian Hackenberg as Memphis' starter, so coach Mike Singletary could look to Manziel to lead his squad.
He immediately becomes one of the biggest names in the AAF as one of its few former National Football League first-round picks, notably among them Birmingham running back Trent Richardson.More news: Fears for Paris Jackson amid reports of hospitalisation
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Manziel had previously said on Barstool Sports' Comeback SZN podcast that he was intrigued by the prospect of playing in either the AAF or the XFL, which begins operation next year. The CFL also effectively barred Manziel from joining any other team in the league.
Manziel has dealt with several off-field issues. He was arrested in 2016 on a domestic violence charge, which was later dropped in exchange for his undergoing counseling.
Manziel was a first-round draft pick by Cleveland, but quickly fizzled out there. Manziel was released by the CFL on February 27, citing Manziel had "contravened the agreement which made him eligible to play in the league".
Information from The Associated Press was used in this report.