Background: Obesity is associated with early mortality and chronic disease among adults with intellectual disability (ID), yet there is a paucity of effective weight management interventions for this population. Objective/hypothesis: This pilot study examined a tailored intervention on weight loss, waist circumference, A1c, and lipid profile among adults with ID. Methods: Obese adults (BMI ≥ 30 kg/m2) with mild to moderate ID were randomized to an intervention (n = 17) or comparison group (n = 18) for a 24-week trial. All participants completed health-related questionnaires and clinic visits. Participants in the intervention group received access to an online weight management platform that assisted them in monitoring their diet and physical activity along with weekly coaching calls (weeks 1–12) that were tapered off to calls every other week (weeks 12–24). The comparison group completed questionnaires and clinic visits, but did not receive access to the online platform or calls. Differences in weight, waist circumference, percent body fat, A1c, lipid profile were assessed at baseline and at week 24. Results: The intervention group reduced body weight by an average of 2.7% (−2.6 kg; p = 0.02) and waist circumference by 3.4% (−3.89 cm; p = 0.02) versus the comparison. There were no statistically significant group by time interactions observed among other variables. Conclusion: Adults with ID who received the intervention were able to maintain or slightly reduce their body weight and waist circumference after the 24-week intervention. Despite not achieving the targeted sample size, the pilot study findings serve as a basis for developing accessible weight management interventions for people with ID.