Background Childhood obesity has become a major focus of public health and subject to increased news coverage. News can shape public understanding of childhood obesity by selective reporting (framing) which can affect policy support and weight stigma. As news is consumed on social media, comments on articles present a novel method to explore public understanding. This study examined how childhood obesity is framed by news articles on Facebook and how individuals commenting understand and react to these articles. Method This study used a qualitative research design. Facebook pages of 11 national UK news outlets were searched for news articles on childhood obesity published between May 2015 and May 2020. Of those, 30 articles were randomly selected. Framing analysis was used to determine whether childhood obesity was portrayed as a behavioral, societal or medical issue. Responding comments (N = 1,104) were grouped according to the dominant frame of the corresponding article and analyzed using qualitative content analysis. Findings Of the 30 articles, 28 mentioned societal, 26 behavioral and 18 medical aspects of childhood obesity, highlighting that most articles included more than one frame. Three themes were generated from responding comments: Culprits and Remedies, Appraising Childhood Obesity and Making Sense of the News Article. Findings showed that comments related to Appraising Childhood Obesity differed between differently framed articles, while the other themes did not. Discussion This study highlights the need for improved communication on childhood obesity to address weight stigma and improve understanding of news articles.