Arrieta was recalled from Norfolk on Saturday to help aid an overworked bullpen, but he didn't appear in a game and hasn't thrown a Major League inning since starting an April 21 contest against the Dodgers.
Manager Buck Showalter said although Arrieta didn't see any game action, he was a nice insurance policy to have, but the team ultimately needed to get him some innings.
"We had two of three options, and felt we needed to get him back on the mound down there and get him pitching again," Showalter said.
Arrieta, who will join Norfolk's starting rotation, has gone 2-1 with a 2.75 ERA in three starts with the Tides.
Gausman, meanwhile, the Orioles' No. 2 prospect according to MLB.com, rose fast through Baltimore's system after being selected with the No. 4 overall pick in the 2012 First-Year Player Draft. In eight starts at Double-A Bowie, Gausman went 2-4 with a 3.11 ERA over 46 1/3 innings. His control has been exceptional, as the 22-year-old struck out 49 batters while walking just five in his first season above Class A ball.
Showalter said Gausman's parents and girlfriend would be in attendance for his debut.
"We brought him up because we thought he could help us," Showalter said.
"It's fun for him. I want him to trust himself and try not to give the level of play too much credit, but also have a respect for it, which he will. We had him with us all spring, so it's a pretty easy transition."
Chris Toman is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.