Although existing literature increasingly suggests a positive influence of pet ownership on human physical activity levels, results from many European, American, and Japanese studies have been inconsistent. How pet ownership impacts mental health and atopy is likewise controversial and whether distinct demographic subgroups experience differential effects is unclear. This cross-sectional study surveyed participants (n = 823) via a self-administered online questionnaire. Comparisons of outcomes between pet owners and non-pet owners with subgroup analyses were performed within a propensity score-matched subset (n = 566) of respondents. There were no differences in physical activity levels or mental health scores between pet owners and non-pet owners. In subgroup analyses, compared to non-pet owners, main pet caregivers reported 14.1 (95% CI 2.79-25.3) and 19.0 (95% CI 4.70-33.3) more minutes per week of moderate- and vigorous-intensity physical activity respectively and higher SF-36 emotional well-being (β = 2.7, 95% CI 0.100-5.32) and energy scores (β = 3.8, 95% CI 0.410-7.27). Age was a significant effect modifier of the association between pet ownership and emotional well-being, energy and social functioning scores, with greater scores above the ages of 39, 35 and 39 years old respectively (interaction p = 0.043, 0.044, 0.042). Finally, pet acquisition was associated with worsening of allergic rhinitis, while pet ownership cessation was associated with improvement of allergic rhinitis and eczema symptoms. To our knowledge, this is the first study addressing the public health impact of pet ownership in Southeast Asia and its findings add contextual nuance to suggest potential benefits derived from pet ownership.