Purpose: The number of people migrating has risen continuously to about 280 million worldwide. International migration involves adapting to new cultural settings while retaining one’s own culture. This process can lead to acculturative stress, a risk factor for migrant health, as well as cultural identity, a key integration outcome. Methods: We investigated the interplay between acculturative stress, well-being (positive and negative affect), cultural identity (national and ethnic identity), and the protective role of physical activity using a 7-day-diary methodology with 266 participants with migration history (1,473 observations). Findings: Daily acculturative stress was associated with lower well-being (positive affect: β = - .05, p = .011; negative affect: β = .05, p = .014) and lower national (β = -.07, p < .001) but not ethnic (p = .343) identity. Physical activity was linked to higher well-being (positive affect: β = .15, p < .001, negative affect: β = -.12, p < .001) and showed a tendency to buffer negative affect associated with acculturative stress (β = -.04, p = .066). Being physically active was not associated with ethnic identity (p = .196) but in tendency with national identity (β = .02, p = .072). Supporting social identity theory, exploratory analyses indicated that stronger cultural identity correlated with higher well-being. Furthermore, cultural identity did not buffer the effects of acculturative stress on well-being but exacerbated them. All analyses were controlled for general stress, highlighting the unique effects of migrant acculturative stress beyond general stress. Conclusions: The findings identify daily acculturative stress as an additional burden for people with migration history, with physical activity offering a potential buffering effect. Interventions targeting migrant health might consider cultural identity and focus on promoting physical activity as a strategy to improve well-being.
