The 27-year-old right-hander was acquired from the Rockies on Thursday for cash.
Paulino takes over for rookie Nate Adcock, who made two starts after moving up from long relief, a role he'll now resume. Adcock lasted only 2 2/3 innings on Friday against the Rangers before Paulino relieved him and tossed 4 1/3 scoreless innings, giving up just one hit.
"If Adcock had had a real decent start, we'd have probably left [Paulino] in the pen," Yost said. "But Paulino has got more weapons right now. He's got a 98 mile-per-hour four-seamer, he's got a 94 mile-per-hour two-seamer, he's got a slider with as sharp a break as I've seen this year -- he was freakin' snappin'."
Paulino had pitched only in relief this season for the Rockies, and his longest outing was 1 2/3 innings and 31 pitches on May 15 against the Padres. So the Royals weren't sure how long he could pitch Friday night in what wound up being a 14-inning, 12-7 Royals win.
"It was a surprise to all of us because I think he hadn't pitched more than 1 2/3 innings at one time this year," pitching coach Bob McClure said. "He threw 56 pitches, which isn't a terrible amount, but he obviously handled it well."
Paulino's pitch count is expected to be up to 65 or 70 pitches in his start next Wednesday.
Adcock pitched five shutout innings in his first start against the Cardinals and gave up seven runs in his 2 2/3 innings against the Rangers.
"Adcock goes back to the place where he's comfortable and it's probably a better fit for him at this point in his career," Yost said.