Objective: To explore parents' responses to sponsorship of children's sport by unhealthy food brands and two alternative pro-health sponsorship options.Design: Between-subjects online experiment with four sponsorship conditions: (i) non-food branding (control); (ii) unhealthy food branding; (iii) healthier food branding; (iv) public health nutrition campaign branding. Participants were shown a short video and a promotional flyer for a fictional junior sports programme, with sponsor content representing their assigned brand. Afterwards, participants were asked a series of questions assessing their brand awareness, brand attitudes and preference for food sponsor branded products.Setting: Australia.Participants: Australian parents (n 1331) of children aged 6-9 years.Results: Compared with the control condition, unhealthy food sponsorship promoted increased awareness, branded product preferences and favourable attitudes towards unhealthy food sponsor brands. Healthier food sponsorship promoted similar effects for healthier food sponsor brands, except there was no significant increase in positive attitudes towards these brands. Sponsorship by public health nutrition campaigns promoted more negative attitudes towards unhealthy food sponsor brands and increased preference for healthier food sponsor branded products. Overall, healthier food sponsors and public health campaign sponsors were perceived to have better programme-sponsor fit and to be more appropriate sponsors of children's sport than unhealthy food sponsors.Conclusions: Restrictions on unhealthy food sponsorship of children's sport are needed to prevent unhealthy food brands from exploiting junior sport sponsorship to enhance their appeal. Sponsorship of children's sport by healthier food brands or public health nutrition campaigns could help promote healthier food choices among parents.