Bonds sat down five pitches later after striking out on a curveball.
"I'm very surprised," said Arias, who spent seven season in the minors before finally getting his shot. "I'm very happy to strike out Barry Bonds. He's the big man."
Matt Holliday homered, hit a three-run double, singled and scored two runs and Arias pitched 3 2/3 scoreless innings for the win in the Colorado Rockies' 9-7 victory over the San Francisco Giants on Tuesday night.
Manager Clint Hurdle moved Holliday up two spots in the order and what a difference it made for the Colorado offense.
Holliday's two-out single in the first got Colorado going while extending his career-best hitting streak to 14 games, the longest active streak in the National League.
He batted third and Garrett Atkins fifth for the first time all season as their skipper switched things up in an effort to increase the team's productivity.
Bonds went 0-for-4 and Bengie Molina blooped a two-run single into shallow right in the first for the first of his three hits, but the Giants saw their six-game home winning streak end.
Brad Hawpe doubled and drove in three runs, hitting a two-run single in the first and RBI single in the seventh. After his double started the fourth, Chris Iannetta hit a go-ahead double to make it 4-3. Russ Ortiz intentionally walked Steve Finley three batters later to load the bases and Troy Tulowitzki hit an RBI single.
"You have to give them credit for laying off some pitches and hitting some good pitches," Ortiz said. "It's just one of those games where nothing went right. I felt like the only bad pitch I threw was the home run."
San Francisco got three straight one-out singles in the fourth and pinch-hitter Mark Sweeney entered with the bases loaded and doubled off the right-field wall to bring home two runs. It was Sweeney's 143rd career pinch hit to tie him with Greg Gross for fourth on the all-time list -- and it also chased Colorado starter Taylor Buchholz.
Arias relieved, giving up an RBI groundout to Dave Roberts that pulled the Giants within 8-6. Arias (1-0), called up Sunday from Triple-A Colorado Springs, allowed one hit with one strikeout and one walk.
"That's a pretty impressive first outing in the major leagues," Hurdle said. "I don't know if I've seen one better than that out of the bullpen. He came as advertised. We saw him in spring training, but that's spring training."
After Manuel Corpas allowed Pedro Feliz's RBI single in the eighth, Brian Fuentes finished for his fifth save in six chances. He struck out pinch-hitter Lance Niekro for the final out with Bonds on deck.
Molina couldn't believe Arias was pitching for the first time in the majors.
"That was his debut? He was impressive," Molina said. "The kid can throw. I've never seen him before, so the first impression was good."
Holliday tied the game at 3 with his fourth homer of the year, a solo shot in the third.
Roberts tripled leading off San Francisco's first and Ryan Klesko singled him in on a bunt one out later before Bonds reached on a fielder's choice. Ray Durham followed with a double and Molina drove them both home.
Ortiz (2-2), trying to win his third straight decision, was done after 3 1/3 innings for his shortest outing of the year after throwing 83 pitches in that span.
The right-hander has a four-start losing streak to the Rockies dating to his last victory over Colorado on May 12, 2005. He allowed a season-high eight runs and nine hits, struck out four and walked two.
Colorado loaded the bases against Ortiz with two outs in the first on singles by Holliday and Todd Helton and Atkins' walk. Hawpe followed with his two-run single.
"He's been throwing the ball fine. He was just off tonight," Giants manager Bruce Bochy said of Ortiz. "The starters have been doing a good job and we'll keep throwing those guys out there."
- Arias struck out swinging in the sixth in his first career at-bat.
- Roberts, the Giants' CF and leadoff hitter, returned to the lineup after nursing an inflamed left elbow on his throwing arm. He hit his fourth triple.
- Hawpe came in batting only .186 (5-for-27) with runners in scoring position.
- The Rockies optioned INF Clint Barmes to Triple-A Colorado Springs and the Rockies recalled INF Omar Quintanilla from Colorado Springs.