In the digital economy, collaboration between human capital and artificial intelligence (AI) provides a critical foundation for enterprises to optimize investment decisions and improve investment efficiency. Taking China’s A-share listed companies from 2018 to 2024 as the research sample, this paper empirically investigates the impact of human-AI collaboration on enterprise investment efficiency. The results show that human-AI collaboration enhances investment efficiency, and analysis based on the varying developmental stages of AI supports this conclusion. Mechanism testing indicates that human-AI collaboration enhances investment efficiency primarily by improving enterprise capabilities in acquiring and analyzing information and by curbing irrational managerial decisions. Heterogeneity analysis from the perspective of “motivation-opportunity-rationalization” shows that the positive effect of human-AI collaboration on investment efficiency is more pronounced in enterprises with larger managerial external pay gaps, higher institutional ownership, and lower strategic aggressiveness. Heterogeneity analysis based on enterprise resource endowments reveals that this effect is stronger among larger enterprises and those facing fewer financing constraints. The test that separates overinvestment from underinvestment shows that human-AI collaboration effectively alleviates both underinvestment and overinvestment. The economic consequences indicate that the impact of human-AI collaboration on investment efficiency ultimately contributes to an enhancement in corporate value. This paper provides practical insights for enterprises on how to build human-AI collaboration mechanisms in the digital economy to enhance investment efficiency and achieve value creation.