Kosier started 80 straight games in which he was active since joining the Cowboys as a free agent in 2006. He helped in the development of Doug Free at left tackle in 2010 while playing left guard and Tyron Smith at right tackle in 2011 while playing right guard.
He did not miss a game in his two seasons but suffered a serious foot injury in 2008 that cost him 13 games. He missed three games with a knee injury in 2010 but did not miss a start in 2011. He was limited in practice for most of the year with plantar fasciitis and suffered a torn medial collateral ligament in the season finale against the New York Giants.
The move will save the Cowboys $1.55 million in salary-cap space. Kosier was due a base salary of $2.25 million in 2012.
In the last three seasons the Cowboys have completely revamped their offensive line, starting with the departure of left tackle Flozell Adams in 2010 and the post-lockout releases of Leonard Davis, Marc Colombo and Andre Gurode last summer.