IntroductionTikTok has over one billion monthly users and is particularly popular among children. We examined the (1) use of owned media by major unhealthy food and non-alcoholic beverage brands on TikTok and (2) nature of branded hashtag challenges instigated by such brands and the user-generated content created in response.MethodsWe assessed the (1) content of all videos posted on the accounts of 16 top food and non-alcoholic beverage brands (based on global brand share) as at 30 June 2021, and (2) content and sentiment of a sample of brand-relevant user-generated content created in response to branded hashtag challenges instigated by these brands.ResultsOf 539 videos posted by brands, 60% were posted in the first half of 2021. The most common marketing strategies were branding (87% of videos), product images (85%), engagement (31%) and celebrities/influencers (25%). Engagement included instigation of branded hashtag challenges that encouraged creation of user-generated content featuring brands’ products, brands’ videos and/or branded effects. The total collective views of user-generated content from single challenges ranged from 12.7 million to 107.9 billion. Of a sample of 626 brand-relevant videos generated in response to these challenges, 96% featured branding, 68% product images and 41% branded effects. Most portrayed a positive (73%) or neutral/unclear (25%) sentiment, with few negative (3%).ConclusionUnhealthy food and non-alcoholic beverage brands are using TikTok to market brands and products via their own accounts and to encourage users to create and share their own content that features branding and product images. Given TikTok’s popularity among children, this study supports the need for policies that protect children from the harmful impact of food marketing on social networking platforms.