AbstractIntroductionResearch has investigated the association between time spent online and mental well‐being, however the nuances between specific online behaviors and well‐being have been less explored. This research examines how specific online behaviors (i.e., how young people are engaging online and with whom), are associated with one another, and how these patterns of behaviors are related to well‐being.MethodsWe used the November 2020 and March 2021 Understanding Society COVID‐19 Panel data. The sample consisted of 1432 adolescents aged 10−15 years, who participated in November 2020. Latent class analysis was used to explore patterns of online behaviors. We also investigated how sociodemographic characteristics differed across the classes, along with physical, social, and mental well‐being as distal outcomes both cross‐sectionally and longitudinally.ResultsWe identified four classes: “Avid users,” “Scholars,” “Midways,” and the “Passengers.” The avid users had the highest frequency of posting online content regularly, likewise the scholars also posted online content regularly, however the scholars were differentiated by their higher frequency of schoolwork and news intake online. The midways had more complex activity characterized by talking to friends often and having a social media account, but posted online content less frequently. The passengers were the least active online as they posted pictures and videos less (76% said “never”) and only 63% had a social media account. The avid users had the lowest well‐being cross‐sectionally and longitudinally, and the midways had lower social well‐being and appearance dissatisfaction.ConclusionsOnline behaviors such as regularly posting or talking to internet‐only friends could be related to lower well‐being. Policymakers should consider both improving regulations online and building an evidence base to enable caregivers from all backgrounds to support young people.