PITTSBURGH — Troy Polamalu never planned on leaving the Pittsburgh Steelers.

Still, the defending AFC champions didn’t want to take any chances, signing the star safety to a contract extension through the 2014 season.

Polamalu, the 2010 NFL Defensive Player of the Year, actually signed the contract at Pittsburgh International Airport on Saturday just before the team boarded a plane to Baltimore.

The 30-year-old took to his Twitter account to announce the deal, tweeting “I am happy to say that I will retire a Pittsburgh Steeler!”

Terms were not immediately disclosed. Polamalu was scheduled to make $6.4 million this season.

The perennial Pro Bowler enjoyed perhaps the finest season of his career in 2010, finishing with seven interceptions, 64 combined tackles and a sack. He was slowed by a strained Achilles in the playoffs and has admitted he was not 100 percent in the loss to Green Bay in the Super Bowl.

Polamalu was ready to start the final year of a five-year deal he signed in 2007. The Steelers typically do not negotiate contracts once the season begins. They got it in just under the wire, saving both sides from a potential distraction over the next five months.

The contract is the third extension the Steelers have handed out to defensive starters since training camp opened. Linebackers Lawrence Timmons and LaMarr Woodley both agreed to long-term deals last month and Polamalu’s signing gives the Steelers stability well into the future.