Older adults spend much time in solitude (without social interaction), putting them at risk of loneliness, especially if aging outside their country of origin (e.g., Chinese immigrants to Canada). Yet, cultural contextual factors that may reduce loneliness in moments of solitude are poorly understood. This study sought to disentangle the roles of culture, immigration, and acculturation in solitude‐loneliness associations across two countries. Community‐dwelling adults aged 51–85 in Vancouver (N = 58 East Asian, N = 37 European/North American) and in Hong Kong (N = 56 East/Southeast Asian) completed approximately 30 ecological momentary assessments over 10 days on their current affect and social situations. Participants in Vancouver spent more time in solitude, desired solitude more, and felt less lonely overall than those in Hong Kong. Multilevel models revealed that moments of solitude felt lonelier than moments spent in social interaction, but only for individuals less acculturated to their host culture or not concurrently desiring solitude. Associations held regardless of host culture, cultural heritage, or immigration status. Findings suggest that solitude need not feel lonely if it happens by choice and if individuals feel connected with their host culture, for both immigrant older adults and those aging in their birth country.