BackgroundState-based Guidelines were issued for Early Childhood Education and Care (ECEC) services (caring for children 0–6 years) recommending greater time outdoors and inclusion of indoor-outdoor programs to facilitate social distancing to reduce spread of COVID-19. The aim of this 3-arm randomised controlled trial (RCT) was to examine the impact of different dissemination strategies on increasing ECEC service intentions to adopt recommendations from the Guidelines.MethodsThis was a post-intervention only RCT. A sample of eligible ECEC services in New South Wales (n = 1026) were randomly allocated to one of three groups; (i) e-newsletter resource; (ii) animated video resource; or (iii) control (standard email). The intervention was designed to address key determinants of guideline adoption including awareness and knowledge. Following delivery of the intervention in September 2021, services were invited to participate in an online or telephone survey from October-December 2021. The primary trial outcome was the proportion of services intending to adopt the Guidelines, defined as intention to; (i) offer an indoor-outdoor program for the full day; or (ii) offer more outdoor play time. Secondary outcomes included awareness, reach, knowledge and implementation of the Guidelines. Barriers to Guideline implementation, cost of the dissemination strategies and analytic data to measure fidelity of intervention delivery were also captured.ResultsOf the 154 services that provided post-intervention data, 58 received the e-newsletter (37.7%), 50 received the animated video (32.5%), and 46 received the control (29.9%). Services who received the animated video had nearly five times the odds (OR: 4.91 [1.03, 23.34] p = 0.046) than those in the control group, to report having intentions to adopt the Guidelines. There were no statistically significant differences in awareness or knowledge of the Guidelines between either intervention or control services. Development costs were greatest for the animated video. The extent to which the dissemination strategy was viewed in full, were similar for both the e-newsletter and animated video.ConclusionThis study found potential for the inclusion of interactive strategies to disseminate policy and guideline information within the ECEC setting, in the context of the need for rapid communication. Further research should explore the added benefits of embedding such strategies within a multi-strategy intervention.Trial registrationRetrospectively registered with the Australian New Zealand Clinical Trials Registry (ANZCTR) on the 23/02/2023 (ACTRN 12,623,000,198,628).Supplementary InformationThe online version contains supplementary material available at 10.1186/s12889-023-16177-7.