To assess, for the first time, the extent (by hour channel) and nature (e.g. persuasive marketing techniques (PMT) and health-related claims) of unhealthy food advertisements (ads) targeted at children (3-11 years) on the six most-watched television (TV) channels in Guatemala. We recorded 864 h of video on the six most popular channels featuring children’s programmes. We classified food and beverage ads as permitted or non-permitted for marketing to children, according to the 2015 World Health Organisation (WHO) nutrient profile. Furthermore, we also analysed PMT (i.e. premium offers, promotional characters, brand benefit claims) and health-related claims. Most food ads (85%) were non-permitted to be marketed to children. Non-permitted food ads were six times more likely, either on weekdays or weekends, for all programme and channel categories compared with permitted food ads. There was no difference in the frequency of non-permitted food ads between peak and non-peak hours, weekend and weekdays or children and non-children programmes. PMT and health-related claims were present in all food ads (5.3 ± 1.9 techniques/claims per ad). There is a need to regulate food ads on TV channels featuring children’s programmes in Guatemala as a result of a high frequency of non-permitted food ads and extensive use of PMT together with health-related claims.