Issue AddressedA lack of programs to develop clinician knowledge and confidence to address weight gain within pregnancy is a barrier to the provision of evidence‐based care.AimTo examine the reach and effectiveness of the Healthy Pregnancy Healthy Baby online health professional training program.MethodsA prospective observational evaluation applied the reach and effectiveness elements of the RE‐AIM framework. Health professionals from a range of disciplines and locations were invited to complete questionnaires before and after program completion assessing objective knowledge and perceived confidence around aspects of supporting healthy pregnancy weight gain, and process measures.ResultsThere were 7577 views across all pages over a year period, accessed by participants across 22 Queensland locations. Pre‐ and post‐ training questionnaires were completed 217 and 135 times, respectively. The proportion of participants with scores over 85% and of 100% for objective knowledge was higher post training (P ≤ .001). Perceived confidence improved across all areas for 88%–96% of those who completed the post‐ training questionnaire. All respondents would recommend the training to others.ConclusionsClinicians from a range of disciplines, experience and locations accessed and valued the training, and knowledge of, and confidence in delivering care to support healthy pregnancy weight gain improved after completion.So What?This effective program to build the capacity of clinicians to support healthy pregnancy weight gain offers a model for online, flexible training highly valued by clinicians. Its adoption and promotion could standardise the support provided to women to encourage healthy weight gain during pregnancy.