He said he will soon file his paperwork with the NFL to make his retirement official.
"Like most NFL players, I wish I could have played a couple more seasons, but usually the league is done with you before you are done with it," he wrote.
"It definitely was a roller coaster ride with many ups and downs and not a lot of years where I felt comfortable with my standing on a team. A dozen years of battling every day to make it another year and to prove myself against some of the best athletes in the world."
Rosenfels, 35, passed for 4,156 yards with 30 touchdowns and 29 interceptions in 44 games with 12 starts. He last threw a pass in a regular-season game in 2008.