Bochy decided to give Winn, an outfielder, a rest from playing the field in Friday night's game against the Royals, the first of nine straight contests at American League ballparks.
"I talked to the guys there, and they thought Randy could use a break," Bochy said. "DH gives him a semi-day off."
Winn has been a DH in 12 games during stints with the Rays and Mariners.
Bochy also announced that catcher Bengie Molina likely would be the club's designated hitter on Sunday.
"It's nice to get guys off their legs and give them a break," the manager said.
The presence of a DH also should give San Francisco's pitchers a break. None of them will have to bat for the next several games. They also won't have to throw against opposing pitchers.
"We've struggled getting pitchers out, so it may help us," Bochy said.
Mark Dent is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.