Jackson, who had started in all 23 games since signing with the franchise as an unrestricted free agent in 2006, has long been regarded as one of the NFL's top interior defenders against the run.
No explanation was given for the release, but sources said Atlanta coaches felt that Jackson was not playing the scheme prescribed for him and was freelancing too much.
The abrupt release of Jackson, who physical presence and ability to demand double-team blocking helped improved the Falcons' run defense in 2006, ends a brief but tumultuous relationship between the team and the player.
In March, Jackson, upset over his contract status, sued the Falcons for defamation and invasion of privacy, claiming team officials had leaked information to the media about the physical examination he took with the club in 2006. Jackson charged that the negative information, which suggested he might have a heart condition, scared off other potential suitors who might have considered signing him.
The lawsuit was eventually resolved and the Falcons reworked Jackson's contract, adding a year to the deal he originally signed in 2006 and providing him a mechanism to earn more money. Under the new deal, the Falcons paid Jackson a $250,000 signing bonus and a roster bonus of $250,000, in addition to his $1 million base salary for 2007.
Jackson, 35, was under contract through 2009, at base salaries of $1 million each year and with roster bonuses of $2 million in the spring of 2008 and 2009.
Although he is a vested veteran, Jackson is subject to waivers claims, since the league's trade deadline has passed. Teams may be reluctant to assume his current contract, but if Jackson clears waivers his run-stuffing ability could make him an attractive free agent for teams seeking tackle help over the second half of the season.
Few players can clog the inside like Jackson and, even at his age, he is still effective.
In 146 career games, Jackson has 440 tackles, 33½ sacks, eight forced fumbles, six fumble recoveries and 26 pass deflections.
The former Knoxville College star began his career with the Oakland Raiders and played there for five seasons (1997-2001). He has also had stints with New Orleans (2002-03), Green Bay (2004-05) and the Falcons (2006-07).
Atlanta, which ranks 22nd in the league in defense versus the run, is expected to move rookie Trey Lewis, a sixth-round pick who has played well in filling in at both tackles spots this year, into the starting lineup.
Len Pasquarelli is a senior writer for ESPN.com.