The complexity of climate change will undoubtedly exacerbate the uncertainty surrounding climate policies, profoundly affecting corporate investment decisions. Enhancing investment efficiency is crucial for achieving sustainable development and serves as the cornerstone for promoting high-quality economic growth in China. Accordingly, this paper delves into the underlying logic of variations in corporate investment efficiency from the perspective of climate policy uncertainty, employing empirical analysis of data from China’s A-share listed companies from 2005 to 2022. Furthermore, it examines the moderating effect of digital transformation on the nexus between climate policy uncertainty and corporate investment efficiency. The findings indicate that climate policy uncertainty significantly diminishes investment efficiency. Digital transformation is capable of significantly mitigating the dampening effect of climate policy uncertainty on the enhancement of investment efficiency. After addressing endogeneity issues and conducting robustness checks, the conclusions remain valid. Mechanism identification reveals that financing constraints, agency costs, and customer stability are critical channels through which climate policy uncertainty affects corporate investment efficiency. Heterogeneity analysis shows that the suppressive effect of climate policy uncertainty is more pronounced in growth-stage enterprises, enterprises with high managerial myopia, and high-carbon enterprises. The moderating effect of digital transformation is more pronounced in declining-stage enterprises, enterprises with low managerial myopia, and low-carbon enterprises. The conclusions of this paper not only provide profound guidance for enterprises to deal with the risks of climate policy changes, but also clarify the key role of digital transformation in addressing climate policy uncertainty, providing significant insights for enhancing corporate investment efficiency.