Background: The growth of the older adult population calls for innovative and cost-effective ways of promoting their physical, psychological, and cognitive health. Human–animal interaction, including pet ownership, is related to positive and negative aspects of human health. Not all pet owners respond in the same way. The levels of pet attachment and pets’ influence on their owners’ lives could moderate the relationship between psychological status and health outcomes. Purpose: We examined the moderating role of pet attachment in the relationships of psychological status (mental wellbeing, happiness, anxiety, depression) to physical function (physical wellbeing, usual- and rapid-gait speeds, physical performance battery) in community-residing older adult pet owners. Methods: A cross-sectional, secondary analysis of pet-owning older adult participants in the Baltimore Longitudinal Study of Aging (n = 178). Results: In regression analyses, controlling for age, gender, and comorbidities, pet attachment and pet influence moderated the relationships of physical wellbeing to mental wellbeing and anxiety (p p Conclusions: Greater attachment and influence buffer the relationship of perceptions of poor mental function with perceptions of poor physical wellbeing suggesting one mechanism for health benefits of human-animal interaction.