Delgado's outing marked the start of the Diamondbacks going to a six-man rotation. Delgado (3-3) started on April 4 and 10, and then made 37 appearances as a reliever.
He came into the game with a 5.85 ERA and held San Diego to two hits in five scoreless innings. He struck out two and walked none.
"First of all, we are happy for the win. I tried to be calm and tried to make quality pitches," Delgado said. "I felt good today. Good defense behind me. I didn't try to do much."
Delgado threw 61 pitches. It was his first career start without allowing a run or walk.
"I think it was the first one in a long time. I felt good about what I did today," he said.
Going to a six-man rotation allows the Diamondbacks to reduce the number of innings for some of their young pitchers and gives others, like Delgado, a chance to win a job for next year.
"Pretty efficient. He just really featured all of his pitches," manager Kirk Gibson said. "Real good performance."
The Diamondbacks won for the fourth time in seven games, including the final two of this four-game series in which they outscored the Padres 11-2.
Ian Kennedy (10-12) had a miserable night against his former team, allowing four runs and 10 hits in 5 1/3 innings while striking out two and walking two.
Kennedy threw 65 pitches through three innings, falling behind 4-0. He allowed five hits in the three-run second, including RBI base hits by Didi Gregorius and Ender Inciarte. Another run scored on rookie third baseman Cory Spangenberg's throwing error.
"I was leaking stuff over the plate early on," Kennedy said. "Made some tough pitches and they put some balls in play that allowed those runs to score in the second inning.
"For the most part, early on, I didn't have my best command early in the counts," he said. "I made tough pitches, but overall I didn't have my command. My curveball wasn't that sharp or my changeup, and I didn't have command of my fastball early on."
San Diego loaded the bases with no outs in the eighth against Matt Stites and scored just one run. Oliver Perez came on and threw a wild pitch that brought in San Diego's only run, and then struck out the side.
Arizona's Aaron Hill started at third base for the first time since his rookie season of 2005 with Toronto. He made a great play in the fifth, laying out to make a backhanded catch of Rene Rivera's liner.
"It was fun. I was hoping for a little more action, but I guess that means our pitchers were doing a great job," he said.
Hill is at third so the Diamondbacks can see if Didi Gregorius and Chris Owings is how they want to go up the middle next year.
Arizona has allowed three runs or fewer in eight straight games, the club's longest streak since doing so in nine consecutive games from Sept. 25, 2005, to April 5, 2006.
The Diamondbacks also won their first season series against San Diego since 2011, going 12-7.
Diamondbacks: Gibson on the return Wednesday night of RHP Daniel Hudson from two Tommy John surgeries: "To see him out there again was very powerful."
Padres: Manager Bud Black said SS Everth Cabrera, on the disabled list with a strained left hamstring, won't make the weekend trip to Colorado but will join the team in Los Angeles and be re-evaluated there.
Padres: LHP Eric Stults (6-15, 4.56) is scheduled to start the opener of a three-game series at Colorado. He's allowed three or fewer earned runs in 11 of his last 13 starts since June 17.