Mora, who will be 39 in February, will split time at third base with fellow veteran Geoff Blum, 37, who was signed to a two-year contract last month.
Mora hit .285 with seven homers and 45 RBIs in 354 plate appearances for the Rockies last season, and he got on base at a .358 clip. Reynolds, meanwhile, hit 32 homers. He also fanned 211 times and hit just .198.
The D-backs set a Major League record for strikeouts with 1,529, and dealing Reynolds was one way to assure they would not challenge for that again.
"We certainly know we're giving up home runs and RBIs, and that's very difficult to replace," Arizona general manager Kevin Towers said. "We think we've got two good defenders [Mora and Blum]. We're not going to lose a lot defensively. Yes, they are up there in age, but they are short-term commitments, they're championship-type players who will add some character to our clubhouse, some leadership to our clubhouse, great pitch recognition, they'll draw walks, they'll put the ball in play and find ways to get on base."
It's part of a restructuring of the club from one that seemed to be three-run homer or bust to one that will be more multi-faceted offensively.
"I think what you'll see when it's all said and done, our ballclub will look a little bit different," Towers said. "A little more emphasis on pitch recognition, less strikeouts, higher on-base guys, contact, hopefully hit-and-run a little bit more and put pressure on the opponent. You can still win that way. We're going to be less the three-run home run, put crooked numbers up in maybe one or two innings; we're hoping to score in every inning, or at least put pressure on the opponent in every inning."
Mora has played for the Mets, Orioles and Rockies during his 12-year career. He has shown plenty of versatility, playing every position on the field other than catcher or pitcher.
"He was such a positive influence to a lot of our younger Latin players," Rockies manager Jim Tracy said. "He did such a special job with those guys. Let's face it, he did absolutely everything you could've asked of the guy when you create the parameters and you're signing him up. He gave you a professional at-bat every time he walked up there. He was willing to take the big at-bats when we needed him. He was very, very special for us. Let's face it, he kept us in the race. When Ian [Stewart] went down, we had to ride him hard."
"Arizona got themselves a good player," Rockies GM Dan O'Dowd said.