He earned a promotion to the Boston Red Sox on July 21 to replace Tim Wakefield, who was placed on the disabled list.

In his major league debut on July 22, he allowed two earned runs in 52⁄3 innings to the Seattle Mariners and was charged with a loss.

Gabbard had a sub-par performance, earning a no decision, and lasted only 31⁄3 innings allowing 4 runs on 6 hits while walking six and striking out two.

Gabbard performed well in his third start of the season on July 2, 2007, allowing three runs on three hits while walking four and striking out five, earning the win.

He tossed his first complete game shutout on July 16, 2007, against the Royals in a 4–0 victory, allowing only 3 hits, 1 walk,[2] and striking out 8.

[7] As of July 27, Gabbard went on a rehab assignment in the Red Sox farm system, pitching for the single-A affiliate Lowell Spinners.

Gabbard's fastball hit the high-80s, his changeup worked the best low and away on right-handed hitters, and his slow curveball was especially effective against lefties.