Objective: This study aimed to evaluate the effectiveness of three levels of exercise on weight regain subsequent to clinically meaningful weight loss (WL). Methods: Adults with overweight or obesity (n = 298) initiated a 3-month behavioral WL intervention, which included reduced energy intake, increased exercise, and weekly behavioral counseling. Participants achieving ≥5% WL (n = 235) began a 12-month behavioral WL maintenance intervention and were randomized to 150 min/wk (n = 76), 225 min/wk (n = 80), or 300 min/wk (n = 79) of partially supervised moderate-to-vigorous–intensity exercise. Results: Participants randomized to 150, 225, and 300 minutes of exercise completed 129 ± 30, 153 ± 49 and 179 ± 62 min/wk of exercise (supervised + unsupervised), respectively. Mean WL at 3 months (9.5 ± 3.1 kg) was similar across randomized groups (P = 0.68). Weight change across 12 months was 1.1 ± 6.5 kg, 3.2 ± 5.7 kg, and 2.8 ± 6.9 kg in the 150, 225, and 300 min/wk groups, respectively. Intent-to-treat analysis revealed no significant overall trend across the three treatment groups (P = 0.09), effects for group (P = 0.08), or sex (P = 0.21). Conclusions: This study found no evidence for an association between the volume of moderate-to-vigorous–intensity exercise and weight regain across 12 months following clinically relevant WL. Further, results suggest that exercise volumes lower than those currently recommended for WL maintenance, when completed in conjunction with a behavioral weight-maintenance intervention, may minimize weight regain over 12 months.