The hard-throwing Bard, whose control troubles ran him out of baseball, pitched 1⅓ scoreless innings in relief while twice getting out of jams as the Rockies beat the Texas Rangers 3-2 on Saturday.
"He said three words: 'That was fun,'" Colorado manager Bud Black said.
Bard's previous big league appearance had been for Boston on April 27, 2013, 11 months after his most recent win.
"It's been a long wait. It feels good,'' the 35-year-old Bard said. "Just trying to soak it in and enjoy every moment."
Bard took over for starter Jon Gray with two on and two out in the fifth. The right-hander, with his fastball in the upper 90s, worked around two more runners in the sixth, getting Willie Calhoun on an inning-ending flyout to cap an 11-pitch at-bat.
Bard threw 20 of his 25 pitches for strikes.
"The stuff is there. ... What a great story," Black said.
Texas manager Chris Woodward played with Bard on the 2009 Red Sox.
"That's why we couldn't get the big hit, there was a higher power involved," Woodward said. "It is pretty cool to see that. Obviously, I'm a baseball fan, so I'm a fan of stories like that. I didn't want to see him get his first win against us."
A first-round pick by the Red Sox in 2006, Bard made his big league debut three years later. He developed control issues in 2012, and the trouble only got worse when he was unable to consistently find the plate with any of his pitches. In his previous appearance, he threw only one strike in his nine pitches.
After several unsuccessful comeback attempts through 2017, Bard spent last year as a player mentor and mental skills coach for the Arizona Diamondbacks. He decided to try one more time and made the Rockies' roster this summer.
"These games are important, but also at the end of the day you're still playing a game," Bard said. "I think the guys that are able to take that mindset into each and every day despite the pressure ... are the ones that have a lot of success. It took me a while to fully grasp that.''
Bard's first pitch was a strike before Elvis Andrus flied out to end the fifth.
"I think with age, you see things differently. Having kids of your own and seeing them grow up, helping them grow up. You just view things different. That doesn't take away, the adrenaline is the same, the juices are flowing. I'm amped to be out there," Bard said. "The difference for me is going back to when I was struggling, you get that feeling, the butterflies, the adrenaline, the heart racing, and it would contribute to all the bad things. It would cause anxiety and basically take away my ability to focus.
"When your perspective is different, you feel those things and you're like all right, it's game time, this is what I'm meant to do."
The Associated Press contributed to this report.