Right-handed reliever Taylor Hill was optioned to Triple-A Syracuse in a corresponding move.
Roark's first 13 appearances of the season were in relief, but when starter Doug Fister landed on the disabled list with a right forearm strain in mid-May, Roark was moved into the rotation.
Roark is 3-0 as a starter with a 3.86 ERA. With Fister back in the rotation and Stephen Strasburg (neck) close to a return, Roark's immediate future will most likely be back in the bullpen.
Hill has pitched in six Major League games this year, with a 3.75 ERA.
Jacob Emert is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.