St. Louis manager Mike Shildt said Saturday that the 24-year-old Flaherty will start the season opener March 26 at Cincinnati. It will be the right-hander's first Opening Day start and comes after he finished fourth in National League Cy Young Award voting with a closing surge last season.
"It's one of those things you work for and you want it," Flaherty said.
The nod comes one season after Flaherty pitched the home opener for the Cardinals.
"It's cool," Flaherty said. "Just happy I get the ball first, get the first chance to go out and kind of set the tone for the season."
Shildt gave Flaherty the news on Friday, not a surprise after Flaherty went 11-8 with a 2.75 ERA last season. Seven of those wins came after the All-Star break, when he posted a 0.91 ERA.
He also started three games in the postseason, allowing eight earned runs in 17 innings.
Flaherty started three games against the Reds last season, allowing one run in 16 1/3 innings while earning two wins.
"It's a nice accomplishment, and it's a well-earned one," Shildt said. "He was excited, but he took it in stride."
Shortly after Shildt made his Opening Day announcement, Flaherty took the mound for the Cardinals' Grapefruit League opener, a 2-0 victory over New York Mets in which he was awarded the win.
Working his scheduled two innings, Flaherty surrendered two hits and struck out three. He threw 20 of his 32 pitches for strikes. His fastball hit 95 mph on the stadium's radar gun.
"Everything felt good," Flaherty said. "It felt comfortable. I felt strong."
Saturday also marked the Grapefruit League debut of left-handed Korean import Kwang-Hyun Kim, known to his teammates as "KK". The offseason signee walked one and struck out two in a scoreless inning.
"I felt KK was good," Shildt said. "Good slider. Located his fastball. Showed a little changeup. Nice outing for him."
Kim is among the handful of pitchers vying for a spot in the Cardinals rotation. Adam Wainwright and Dakota Hudson will join Flaherty as starters. Miles Mikolas would have broken camp in the rotation, but a flexor tendon issue will force him to miss the opening weeks of the season.