Kelley will be called up from Triple-A Pawtucket on Tuesday.
Kelley had a 0.96 ERA, 1.06 WHIP and 34:12 K:BB over 37.2 innings at Pawtucket this season. The 25-year-old figures to start out in a low-leverage role, but he could see higher-leverage chances with a good first impression given Boston's bullpen issues.