The surface integrity of gears is a critical factor that directly determines their rolling contact fatigue life. This study investigates how shot peening, a surface treatment process that generally introduces both elevated surface roughness and high compressive residual stress, affects the surface integrity and rolling contact fatigue performance of 18CrNiMo7-6 gear steel rollers (denoted as SP roller), in comparison to their unpeened counterparts (denoted as SG roller). Failure was defined as a spalling crater spanning the full roller width. Although the SP roller shows less severe surface fatigue damage (characterized by smaller spalling crater length and area), its fatigue life is 25.5% shorter than that of SG roller. Analyses indicate that the life reduction primarily stems from the formation of multiple crack initiation sites across the entire width of the roller. These distributed crack sources accelerate the processes of crack initiation and propagation, which in turn leads to the rapid development of a dominant full-width surface spalling crater.