People with intellectual and developmental disabilities (IDD) face difficulties in making lifestyle changes because of lack of community and professional awareness and specialist services. Some services, such as for health wellness, are even more difficult for people with IDD to acquire if they live in remote areas or they cannot access specialist services in their community. Telehealth is beginning to be used to fill this service need. In this study, we assessed the effectiveness of providing telehealth training to parents on a mindfulnessbased healthwellness (MBHW) program that they then taught their children to implement. Thirty-two overweight or obese adolescents and young adults were taught a five-componentMBHWprogram, and its effects on their body weight were assessed within a changing criterion design. The intervention included physical exercise, healthy eating and nutrition, mindful eating, mindful response to thoughts of hunger, and amindfulness practice to control the urge to eat. The 30 participants who successfully completed the whole program had an average weight of 164.2 lb at baseline (pre-intervention), lost an average of 38.27 lb by the end of intervention, and maintained their target weight for four consecutive years at a mean weight of 127.37 lb. On average, they reduced their body mass index (BMI) from a mean of 29.54 at entry into the program to 22.80 by the end of intervention, andmaintained their BMI at a mean of 23.03 during the 4-year follow-up. In addition, the participants’ social validity ratings showed great satisfaction with the program in meeting their desired weight goals, and they unanimously indicated that theywould recommend the program to their peers. The data suggest that theMBHW program was effective with the participants and further evaluation using a randomized controlled trial appears warranted.