Women who undergo breast cancer surgery risk suffering from postsurgical pain long after their surgery. Still, research on postsurgical pain in the subacute phase has been neglected. This study aims to investigate the incidence, intensity, unpleasantness, and presurgical predictors of acute and subacute postsurgical pain after breast cancer surgery. The study used an observational design through secondary analyses of the control group in a randomized controlled trial. Data from 102 women undergoing breast cancer surgery were included. Levels of acute and subacute pain intensity and unpleasantness were measured using 100 mm Visual Analogue Scales on the day of surgery and 4 weeks postsurgery. Linear regression analyses were performed to identify presurgical biopsychosocial predictors of acute and subacute postsurgical pain. Average levels of postsurgical pain intensity and unpleasantness were as follows: 22.7 mm for acute pain intensity, 19.0 mm for acute pain unpleasantness, 10.3 mm for subacute pain intensity, and 11.7 mm for subacute pain unpleasantness. Pain expectancy predicted acute pain intensity (R2 = 0.04, p = 0.047) and acute unpleasantness (R2 = 0.06, p = 0.02). Perceived social support inversely predicted acute pain unpleasantness (R2 = 0.04, p = 0.014). Mild and moderate acute pain intensity and unpleasantness are common after breast cancer surgery, whereas levels of subacute pain intensity and unpleasantness are low. Pain expectancy predicts acute postsurgical pain intensity and unpleasantness, whereas expected social support inversely predicts acute postsurgical pain unpleasantness.