Atlanta announced the deal Wednesday. Trufant's agent, Doug Hendrickson, told The Associated Press that the contract was for $8.16 million with $4.3 million guaranteed.
"Desmond is very excited to get started," Hendrickson said. "He made it clear he wanted to be in camp on time. As usual, the Falcons were great to work with, and we're glad to get this deal done."
Trufant was one of the first players to report to dorms at the team's training facility in Flowery Branch, Ga. Camp officially begins on Thursday with the first practice.
Atlanta traded up eight spots in a draft-day deal with St. Louis to select Trufant out of Washington. He is the leading candidate to start at right cornerback but will have to beat out Robert Alford, a second-round pick from Southeastern Louisiana.
In six years under general manager Thomas Dimitroff, the Falcons have had only two players not report on time because of a contract dispute.
Offensive tackle Sam Baker missed the first practice of camp in 2008. Veteran wideout Roddy White missed the first eight days of 2009 before signing a six-year deal that made him one of the NFL's highest-paid receivers.
Trufant was the last of eight draft picks this year to finalize a contract with the Falcons. Quarterback Sean Renfree, a seventh-round selection from Duke, signed Wednesday, too.
Trufant has two brothers with NFL experience in the secondary. Marcus Trufant played his first 10 seasons in Seattle before signing with Jacksonville two months ago. Isaiah Trufant, a career reserve, is preparing for his fourth season with the New York Jets.
Desmond Trufant is competing with Alford to replace Dunta Robinson, who signed with Kansas City in March after the Falcons released him to clear salary cap room.
Atlanta lost former starting cornerback Brent Grimes and former reserve Christopher Owens to unrestricted free agency.
The only current Falcons cornerback with substantial starting experience is Asante Samuel, a four-time Pro Bowl pick who holds the left-side job.