Crisp, on the disabled list with a broken finger, was already signed for this year at $2.75 million. The extension contains a $1 million signing bonus and salaries of $3.5 million in 2007, $4.75 million in 2008 and $5.75 million in 2009. The deal contains an $8 million team option for 2010 with a $500,000 buyout and contains salary escalator provisions.
Before the extension, Crisp's contact was set to expire at the end of the year, but he would have been eligible for arbitration through 2009, which would have kept him in Boston until then.
Crisp said his short time in Boston convinced him it was worth giving up his first shot at free agency.
"I was able to hang out with the guys and the front office and see what they were like," Crisp said. "I had fun with the guys. Being with the Red Sox made it easy. You want the security and having that, and playing for the Red Sox, is great. There's no better place to be."
The 26-year-old center fielder was acquired by Boston in a six-player deal with Cleveland during the offseason and replaced Johnny Damon, who left to sign with the New York Yankees. Crisp, who bats leadoff, had his best season last year in Cleveland, when he hit .300 with 86 runs scored, 16 homers and 15 steals.
This season, Crisp was hitting .333 (8-for-24) with six runs scored in five games before breaking his left index finger while trying to steal third last Saturday in Baltimore.
Crisp's extension came two days after the Red Sox signed David Ortiz to a $52 million, four-year extension through 2010.
Red Sox general manager Theo Epstein said talks about a Crisp extension heated up late in spring training and the deal had been done for a while.
"We think investing in Coco was a wise move," Epstein said Wednesday.