Customer strategic alliances (CSAs) can reduce the underpricing of initial public offerings (IPOs) for Chinese firms. Firms with CSAs have lower underpricing compared to those without such relationships, especially if they have non-related-party customers. This decrease in underpricing is more significant for firms with a good pre-IPO information environment, like high audit quality and analyst following. CSAs also positively impact a firm's post-IPO performance, particularly when they involve non-related-party customers. Overall, CSAs help to lower IPO underpricing and improve returns after the IPO.