A large body of research has explored various factors influencing volunteer participation, particularly revealing the association between religious beliefs and volunteer engagement. However, there was relatively limited research on volunteer participation among international immigrants in China, a newly emerging immigrant country. Further investigation was needed to identify the factors influencing the volunteer engagement of international immigrants in China and the underlying mechanisms. This study analyzed data from international immigrants in Yiwu, China and found that their volunteer behavior was significantly influenced by their religious beliefs. Additionally, social resources were closely related to their volunteer participation. Furthermore, although perceived discrimination among international immigrants in China was not directly associated with volunteer participation, it promoted their religious participation and frequency, consequently encouraging their volunteer engagement. Further analysis also revealed two mechanisms through which religion impacted volunteer participation. On the one hand, religious beliefs influenced volunteer participation through the mechanism of religious indoctrination. On the other hand, though perceived discrimination among international immigrants did not directly influence volunteer participation, it did encourage them to engage in religious meetings to establish social networks for support, thereby enriching their social resources and subsequently promoting volunteer engagement. We discussed the implications of our findings for encouraging volunteer participation and for promoting the social integration of international immigrants.