Background: Studies assessing the effects of parenting programs have focused on interventions delivered through face-to-face modalities. There is a need for research to evaluate the effects of online parenting programs on child development, such as the BEM Program ('Play Teaches Change' in English), an online play-based parenting program that teaches caregivers on how to introduce playful interactions into their daily household chores. Objective: To assess the effects of the BEM Program on child development and the quality of caregiver-child interaction. Method: A two-arm randomized controlled trial was conducted in a socioeconomically disadvantaged district of São Paulo city in Brazil. 129 children aged 12-23 months and their caregiver were randomly assigned to receive either the BEM Program for 8 weeks (intervention, n = 66) or standard child care (control, n = 63). Data were collected at baseline and endline of the intervention through home visits and online interviews. An intention-to-treat analysis was conducted. Results: The intervention showed positive effects on child development, by improving language development (Cohen's d = 0.20, 95%CI 0.08-0.47) and reduced intrusiveness (Cohen's d = 0.35, 95%CI 0.06-0.65) of caregiver-child interaction. No significant differences were observed in caregiver's repertoire and engagement in age-appropriate play activities with the child while doing the household chores, parenting sense of competence and perceived stress. Conclusions: Despite the small size and low adherence to the program, such promising results advance evidences for fully remote parenting programs and their effects on child development.