This paper selects a sample of cross-border M&A events by Chinese acquirers over the period 2000-2021 and uses a multiple regression model to investigate the relationship between acquirer’s carbon risk and M&A performance. On the one hand, it explores whether the acquirer’s carbon risk promotes M&A performance and whether the selection of other developing economies as host countries by Chinese acquirers can strengthen the above relationship. On the other hand, the impact of changes in post-merger carbon risk on M&A performance is explored. The results show that: (1) The higher the acquirer’s carbon risk the better the post-merger performance, but this relationship is not strengthened by the choice of other developing economies as the host country. (2) For acquirers with high initial carbon risk, their M&A performance increases if the post-merger firm reduces its carbon risk by practicing CSR, etc.; for acquirers with low initial carbon risk, there is no significant relationship between M&A performance and the change in carbon risk. Our findings contribute to further understanding of the impact of acquirers' carbon risk on M&A performance.