Summary Background Although early childhood obesity prevention has become an important issue internationally, little evidence exists regarding longer term effects (i.e., sustainability) of early interventions. Objective To determine whether intervention benefits at 2 years of age were sustained at 3.5 and 5 years. Methods Follow‐up of the Early Prevention of Obesity in Children (EPOCH) individual participant data prospective meta‐analysis of four randomized controlled trials including 2196 mother–child dyads at baseline. Interventions were home‐ or community‐based, commenced within 6 months of birth, ended by 2 years of age, and comprised multiple sessions. Controls received standard care. BMI z‐score (primary outcome), other anthropometric measures and weight‐related behaviours were initially measured at 1.5–2 years and followed up at 3.5 and 5 years. Results Positive intervention effects on BMI z‐scores at 1.5–2 years of age were not apparent by 3.5 years (−0.04 adjusted mean difference; 95% CI:−0.14, 0.06; p = 0.424), and 5 years (0.03; 95% CI: −0.08, 0.14; p = 0.60). While prolonged intervention benefits were detected for a few, but not the majority of, weight‐related behaviours at 3.5 years, these effects diminished over time. Conclusion This meta‐analysis found that initial positive effects of childhood obesity interventions faded out after interventions ended, pointing toward the importance of a suite of interventions implemented at multiple stages across childhood.