BackgroundResearch has indicated that the effectiveness of intervention programs is affected by how well these programs are implemented, but key gaps remain in our understanding of the factors that promote or inhibit implementation. This study examined how demographic characteristics and perceived work environment among early childhood educators were associated with implementation outcomes of the Increased Health and Wellbeing in Preschools (DAGIS) intervention, which was conducted as a cluster randomized trial.MethodsParticipants included 101 educators from 32 intervention preschool classrooms. Data were analyzed at the classroom level, as the DAGIS intervention was delivered in preschool classrooms consisting of several educators instead of individual implementers. Linear regression was used to estimate the associations of educators’ demographic characteristics and perceived work environment with different aspects of implementation (i.e., dose delivered; dose received – exposure; dose received – satisfaction; and perceived quality, as well as a total sum score based on these four dimensions). Municipality was controlled in the adjusted models.ResultsFindings indicated that having a higher proportion of educators with a Bachelor’s or Master’s degree in education within the classroom was associated with higher dose received – exposure and higher total degree of implementation, and the significance of the models was unaffected by adjustment for municipality. Moreover, having a higher proportion of educators younger than 35 years within the classroom was associated with higher dose received – exposure. However, the association was non-significant when adjusted for municipality. No other educator factor (i.e., work experience in years and perceived support from coworkers, group work, and innovative climate) predicted implementation outcomes.ConclusionsHigher educational attainment and younger age among educators at the classroom level were associated with higher scores for some of the implementation outcomes. Educators’ work experience in years at the current preschool and in early childhood education, support from coworkers, group work, and innovative climate were not significantly associated with any implementation outcomes. Future research should explore ways to improve educators’ implementation of interventions aimed at promoting children’s health behaviors.Supplementary InformationThe online version contains supplementary material available at 10.1186/s13690-023-01133-z.