The Orioles' right-hander made his Major League debut during the eighth inning of a 5-1 loss to the Red Sox. He retired Boston in order, getting Travis Shaw and David Ortiz to ground out before striking out Mike Napoli.
"My heart was pounding a little bit, but after the first pitch, it went away," Givens said. "I just wanted to treat it like any other game, but just go out there and live in the moment."
Baltimore manager Buck Showalter was impressed with Givens' fastball command after not pitching the past six days.
"I wanted him to start the inning clean. He had six days off, a lot of adrenaline going," Showalter said. "You can see why everybody is excited about his stuff."
After warming up a few times since being called up Saturday, Givens admitted he was anxious to finally get into a game.
"It felt like a long time, but I had to sit back and wait for my name to be called," Givens said. "The few times I got warmed up and was hot, the adrenaline was going and my heart was beating. I was just trying to take everything in and enjoy the path I've been on."
The 25-year-old went 3-1 with a 1.60 ERA and 12 saves in 23 games with Double-A Bowie this season.
A second-round Draft pick of the O's in 2009, Givens made the transition from shortstop to pitcher two years ago.
"I'm just living in the moment and trying to do my best," Givens said. "It has been a little bump in the path with playing shortstop and now being a pitcher, but now since it's done, I'm happy to be here."