Central to the intercultural experiences of international students is the formation of various social contacts, which play a crucial role in their intercultural development. This study employs a mixed-methods approach to investigate the patterns and functions of social contact among Chinese students at UK universities and their impact on intercultural sensitivity. A self-report survey (N = 102) was utilized to assess both the quantity (amount and frequency) and quality (strength, closeness, and pleasantness) of contacts with three social groups: co-nationals, host nationals, and non-co-nationals, examining their effects on intercultural sensitivity. Pearson’s correlation and multiple regression analyses were employed to examine the relationships among variables. Semi-structured interviews (N = 13) were conducted to further explore the nuances of these relationships and a thematic analysis was carried out. Despite challenges in forming social ties with host nationals, our findings indicate that both the quantity and quality of interactions with host nationals significantly enhance international students’ intercultural sensitivity, especially in the aspects of interaction confidence, engagement, and attentiveness. The study highlights the pivotal role of host nationals in facilitating the intercultural development of international students and calls for institutional and educational practices in UK higher education to promote frequent and meaningful interactions between international students and host nationals.