Based on the supply chain perspective, the impact of customer stability on corporate financial asset allocation and its mechanism are examined with A-share listed companies in China from 2010 to 2022. The research results show that customer stability can significantly inhibit corporate financial asset allocation behavior, and business risk, financing constraints, and agency costs play a mediating role. In further research, it is found that the inhibitory effect of customer stability on firms’ financial asset allocation is more pronounced in firms with better customer relationships and low social trust, and the main inhibition is on long-term financial asset allocation behavior. In the test of economic consequences, it is found that customer stability can actively guide enterprises to return to the main business while inhibiting the allocation of corporate financial assets, and significantly promote the investment in industrial assets and the improvement of the performance of the main business. The above conclusions provide micro-level empirical evidence for curbing enterprises’ tendency towards financial investment by stabilizing the supply chain, so as to achieve high-quality development based on their own real industries.