With a full 40-man roster, the Orioles also designated outfielder Joey Rickard for assignment to create room for Gilmartin.
In 17 games with Norfolk, Gilmartin registered a 2.48 ERA and 1.10 WHIP over 36 1/3 innings to position himself as an alternative for a team that’s routinely making changes to its rotation and bullpen.
Gilmartin, 29, most recently shut out Toledo over three innings on Friday night at Harbor Park. He hasn’t allowed a run in his last four appearances covering 9 1/3 innings.
The Orioles outrighted Gilmartin on Nov. 1 and he elected free agency before agreeing to a minor league deal the following day. He received an invitation to spring training and allowed three earned runs and four total in three innings.
Gilmartin posted a 3.00 ERA in 12 relief appearances last summer and allowed only two runs in his last four games totaling 13 2/3 innings. The Orioles signed him on July 13.
Manager Brandon Hyde could decide to use an opener and Gilmartin might be a candidate.
Rickard, 28, broke camp with the team but was optioned on May 23 after batting .203/.304/.347 in 42 games. The Orioles acquired center fielder Keon Broxton from the Mets the previous day and his arrival pushed Rickard to the minors.
The starting right fielder on opening day, Rickard appeared in 18 games with Norfolk and batted .203/.338/.469 with five doubles and four home runs. His last homer came two days ago.
The Orioles selected Rickard from the Rays organization in the 2015 Rule 5 draft. He’s a career .245/.299/.372 hitter in 317 major league games.
Rickard tumbled down the outfield depth chart, with the Orioles carrying Anthony Santander on their active roster and waiting for Dwight Smith Jr. to come off the concussion injured list and former first-round pick DJ Stewart to be activated from the 10-day injured list.
The Orioles can attempt to trade Rickard, release him or outright him if he clears waivers.
Gilmartin is replacing David Hess, who was optioned to Norfolk after yesterday’s game. He will wear No. 63.