Adams picked up the 2007 option on Fisher's contract at the end of last season, and an extension had been expected since then. Fisher said they finally worked out the last details last week.
"Never at any time was I of the opinion it was not going to get done," Fisher said. "What was most important to me was the team and the players and winning games."
Fisher is in his 13th season with the franchise that used to be the Houston Oilers. He originally was promoted from defensive coordinator to interim head coach in November 1994 and had the interim tag removed after that season ended. He coached his 200th regular season game with the Titans in Sunday's 22-20 loss to Indianapolis.
He is 18-32 since the team's last playoff berth and winning record in 2003.
But the Titans have won seven of their last nine games going back to last season when they rallied from an 0-5 start to an 8-8 finish that was one victory shy of a playoff berth with Offensive Rookie of the Year Vince Young.