Adams was coming off his 12th season and was the longest-tenured player on the team, having started 178 of his 182 games for Dallas. All of his Pro Bowl selections came between 2003-08.
"We will always be grateful for his outstanding durability, dependability and contributions to this team," owner Jerry Jones said in a statement. "I don't know that you could ask for any more than what Flozell Adams gave to the Dallas Cowboys for 12 seasons."
Hamlin was a Pro Bowl pick in 2007, his first season in Dallas after spending the first four years of his career in Seattle.
"We appreciate what he brought to this team, and this defense, as a solid player and a competitor," Jones said of Hamlin.
Adams and Hamlin both signed six-year deals through 2013 before the 2008 season. Adams could have been a free agent then, but never hit the market before signing his $43 million deal with the Cowboys, who drafted him in the second round out of Michigan State in 1998.
Adams, who turns 35 in May, was due a $2.5 million roster bonus in June and a $5 million base salary for the 2010 season. Hamlin's base salary this season was to be just over $5.5 million.
Hamlin set career highs with 102 tackles and five interceptions his first year in Dallas, but his numbers have decreased since getting his $39 million deal. He had 92 tackles with one interception in 2008, and 74 tackles with no interceptions last season, when he missed four games with a high ankle sprain.