Snyder, who will turn 28 in February, will make a guaranteed $14.25 million with the possibility of getting as much as $20.25 million if the option is picked up.
Snyder will make $3 million in 2009, $4.75 million in 2010 and $5.75 million in 2011. The club option would pay him $6.75 million, or he would receive a buyout of $750,000.
"Having Snydes behind the plate for the next two years will be great," said D-backs ace Brandon Webb, who is under contract through next season with a club option for 2010.
Snyder hit .237 with 16 homers and 64 RBIs in 2008. His OPS-plus, which is a weighted form of on-base percentage plus slugging, was 103 -- meaning he was three percent above average offensively.
Snyder has made big strides at the plate since his first full year in the big leagues, 2005, when he hit .202.
Snyder has always had a supporter in manager Bob Melvin.
"We've had a great relationship," Snyder said. "I know he's had my back many times. It's great having him as a manager because as an ex-catcher, he knows what I'm going through."
Snyder keeps himself in excellent physical shape, thanks in part to an offseason workout program that includes Mixed Martial Arts training.
"I take pride in what I do," Snyder said. "I enjoy what I do and feel blessed to be able to do what I do, so I work hard on all aspects of my game. It's a never-ending thing. It's just part of the job."
While his offense has improved, it's Snyder's work defensively that makes him a favorite among the pitching staff.
"Snydes has a good idea of what he is doing back there," Webb said. "He studies the hitters a lot and can adjust with them as the game goes along. As for the team, I am sure they feel the same way. I think everybody likes having Snydes back there calling the game and feels very comfortable with him."
"He handles the defensive part and the intangible side of the position very well," Arizona general manager Josh Byrnes said. "It's almost immeasurable. At the same time, he's also been a pretty good offensive player."
The extension buys out two years of salary arbitration for Snyder as well as at least one year of free agency. It's another example of the D-backs trying to lock up their young players before they hit free agency, and in some cases before they even become eligible for salary arbitration.
The D-backs have worked similar deal with young players like outfielder Chris Young, infielder Chad Tracy and pitchers Dan Haren and Webb. It's a course the club could also pursue with Conor Jackson, Stephen Drew or Justin Upton.
"It allows us to keep the core group together," Byrnes said of the deals, which give the players security while the club gets cost certainty.
The D-backs have good reason for wanting to keep their team intact. It's a group that won the National League West in 2007 and finished second to the Dodgers last season.
"We have a great group of young guys," Snyder said. "If we stay together, we'll be contending in the NL West, if not further than that. It's a great clubhouse. We have a great time doing what we do. We have a great time playing."