YouTube is the dominant online video-sharing platform and offers zoos an opportunity to engage a vast audience with conservation content. As there is limited research evaluating how zoos currently utilize YouTube, we cataloged and evaluated the content of 20 zoological organizations (focusing on the top 1000 most viewed videos from each channel) from 2006 to 2019. Separately, educational content in a subsample of the most viewed and recently produced videos from three zoo-YouTube channels was catalogued and evaluated for the period 2016 to 2019. We found that channels are becoming more focused on producing entertainment, rather than education-based content and not reflecting the taxonomic diversity of their animals. Videos containing conservation content may not be the most popular with the YouTube audience (making up only 3% of the most viewed videos), but there is evidence that outputs are becoming more conservation orientated, with more conservation-focused videos being produced over time. Zoos may be engaging with large audiences via YouTube, but should carefully consider how they represent different taxonomic classes and how they can create educational material in interesting and accessible forms.