The COVID-19 pandemic has resulted in significant social disruptions for youth caused by lockdowns, school closures, and a lack of in-person social interactions. Companion animals are prevalent in US households and may provide a source of emotional support and motivation for youth to engage in adaptive coping behaviors during social challenges. The goals of this study were to assess if dog owners, non-dog pet owners, and non-pet owners differed in stress levels, positive affect, and use of adaptive coping strategies such as increased time outdoors, regular walking, and healthy behaviors. This study used data collected during the COVID-19 pandemic from the Adolescent Brain Cognitive Development SM (ABCD) Study, a large, nationally representative dataset of American youth. In a cross-sectional sample of 6,069 adolescents, there were significant, but small, relationships between owning a non-dog pet and lower levels of positive affect, and both dog owners and non-dog pet owners reported higher perceived stress compared with non-pet owners. Dog ownership was associated with higher odds of using healthy coping strategies compared with non-pet owners, but this relationship was not significant when controlling for demographic variables. Dog owners reported higher odds of having a walking routine and spending time outdoors compared with non-pet owners. Overall, the results suggest no buffering effect of pet ownership on youth mental wellbeing, but dog ownership is associated with some healthy coping behaviors linked to walking.