Parental promotion of an adequate environment during early childhood results in healthy child development. This study evaluated the feasibility and effectiveness of the positive parenting programme, `Gaining health and wellbeing from birth to three´ (GH&W), as a universal prevention strategy. Participants were 87 parents with children < 36 months old attending 20 primary care centres. Centres were randomly assigned to three GH&W intervention levels: online course (level 1), online course plus group workshops (level 2), and online course plus group workshops plus individual support at medical check-ups (level 3), delivered by healthcare professionals. As for feasibility, participants in levels 2 and 3 reported higher utility and satisfaction with the online course than participants in level 1. Pretest-posttest comparisons and cluster analysis showed that participants in level 3 achieved the best results and were associated with a consolidated cluster characterised by improvements in health promotion activities, parental self-regulation, and satisfaction with the service, whereas participants in levels 1 and 2 showed fewer improvements and were associated with initial and transitional clusters. The GH&W programme improves the universal reach of web-based courses and efficiently activates the contribution of the primary care system to the support network for healthy child development and wellbeing.