This study examines how neighborhood walkability, third place engagement, and socio-demographic characteristics affect leisure-time physical activity and social capital among older adults. It also investigates how these relationships differ between those living alone and those living with others. Data for this study were collected via an online survey administered to 638 older adults, aged 65 and above, residing in Orlando, Florida. Ordinary least squares (OLS) regression models were employed. Frequent visits to third places significantly increased moderate leisure-time physical activity and social capital. Neighborhood walkability also played a crucial role in promoting physical activity and social capital. The availability and condition of sidewalks also played a positive role in promoting physical activity. Enhancing neighborhood walkability and promoting third place engagement can be key strategies for improving both physical and social well-being among older adults, especially those living alone.