The win snapped the D-backs' four-game losing streak and it was another in a string of outstanding outings by starter Daniel Hudson.
In nine starts for Arizona since coming over from the White Sox in exchange for Edwin Jackson on July 30, Hudson is 6-1 with a 1.67 ERA.
"He has good stuff," Reds manager Dusty Baker said. "That's a heck of a trade for them. They gave up a no-hit pitcher in Jackson and got a potential great pitcher there."
On Tuesday he handcuffed the Reds for eight innings as he allowed four hits and walked one while fanning eight.
"I was kind of struggling with my slider command in the beginning, kind of yanked a couple of them," Hudson said. "Finally I was able to add that in a little more and got a couple of strikeouts on it. It was a big pitch for me to be able to find that."
The D-backs have won two of their past 10 games and both times it was Hudson that got the victories.
"Just to be able to get in a little bit of a groove, it feels real good to go out there and get a couple of wins for the team," Hudson said. "Right now my confidence is very high and it's a great, great feeling right now."
Reds starter Travis Wood (5-3) matched Hudson through the first three innings as he fanned five and allowed just two hits over that span.
However, the D-backs adjusted to him in the fourth, becoming more aggressive early in the count. That resulted in a two-run inning, with Mark Reynolds singling in the first run and Hudson helping his own cause with a two-out RBI hit.
The D-backs again scored in the fifth when Tony Abreu led off with a double and scored when Justin Upton followed with a single to center.
Hudson was at 106 pitches after eighth innings and D-backs interim manager Kirk Gibson did not want to overextend him, so he turned to Gutierrez in the ninth.
"We knew he was our best pitcher going," Gibson said. "Unfortunately he ran out of pitches."
After allowing back-to-back singles to start the inning, Gutierrez fanned the next two hitters. Jay Bruce then drew a walk and Gutierrez hit Drew Stubbs with a pitch to force home a run.
That brought Hernandez to the plate and Gutierrez immediately fell behind him, 2-0.
Hernandez smoked the next pitch to right, which, off the bat, looked like it had the potential to clear the bases and give the Reds the win.
"He put a good swing on it," said Hudson, who was in the dugout at the time. "I didn't know what to think at first. I saw Upton got a good break on it and he made a heck of a play to end the game, and that's all you can ask for."
Upton, though, knew right away he had a chance to make the play as he raced to the gap in right-center and reached up and snared the ball on a dead run.
"With him, I wasn't playing so much to right field. I was playing more to the gap because he drives balls out there," Upton said. "Once it came off the bat I knew I had a bead on it. Actually, it kind of went up in the lights a little bit and I was a little hesitant whether I was going to catch it or not, but it came out once I got beyond the lights and I was able to snare it."
Said Gibson, "J-Up made a good play. He got a great jump on the ball and he has very good speed and he covered a lot of ground very quickly."
Hernandez slammed his helmet down in frustration after Upton made the catch.
"He's a good athlete and very fast," Hernandez said. "He got a good jump after I hit it. It was a great play. You have to tip your hat to a guy that can make a good catch like that, especially to end the game."