In today’s globalised world, people are interacting with different cultural streams every day, which can challenge the individual’s rootedness in regard to their identity. The purpose of the present study is to examine the relationship between social identity and well-being in terms of satisfaction with life, and to examine whether the individual’s reaction to cultural globalisation mediates this relationship. The individual’s reaction to cultural globalisation was operationalised as a proactive (multicultural acquisition) or defensive (ethnic protection) reaction. The study examined students in India ( n = 147) and Denmark ( n = 223). The results showed that social identity was positively related to well-being in Denmark but negatively related to well-being in India. Moreover, it showed that social identity and well-being was mediated by a defensive reaction to cultural globalisation in both contexts. The results indicate that cultural differences affect how the individual reacts to cultural globalisation and, further, how social identity and well-being are related. Therefore, the relationship between social identity and well-being in globalised contexts is complex and it is relevant to include the individual’s reaction to cultural globalisation when comprehending the role of social identity in globalised societies.