His release had been earlier reported by the team website.
Hargrove, who did not play in 2012 after serving an eight-game suspension for his role in the New Orleans Saints bounty scandal, signed a one-year, veteran-minimum deal with the Cowboys on May 16.
He struggled with his conditioning during his short stint with the Cowboys, spending several organized team activity sessions working out on the side.
He was also suspended for the 2008 season for violating the league's substance-abuse policy. He was cut by the Green Bay Packers in August last year and spent the rest of the season out of football.
Hargrove, 29, has 19.5 sacks for four teams during his eight NFL seasons.