Against the backdrop of the high-quality development of the digital economy, exploring the impact of data assetisation on corporate investment efficiency with fintech as the core tool is of great significance for driving the steady and orderly development of enterprises...Taking A-share listed companies from 2012 to 2023 as the research sample, and further classifying them into self-used data assets and transactional data assets based on the types of data assets., the study finds: (1) Data assetisation significantly enhances corporate investment efficiency, with self-use data assets demonstrating a stronger driving effect.(2) Mechanism analysis reveals that data assetisation alleviates underinvestment by easing financing constraints and leveraging the "talent effect". Concurrently, it mitigates overinvestment by reducing agency problems and accelerating digital transformation, thereby enhancing investment efficiency. (3) Heterogeneity tests indicate that the positive impact of data assetisation on investment efficiency is more pronounced among growth-stage enterprises, technology-intensive firms, and companies operating in regions with high bank liquidity.(4) Banking fintech positively moderates the enhancement of corporate investment efficiency through data assetisation, with a more pronounced effect on alleviating underinvestment. However, it may also exacerbate overinvestment. Consequently, enterprises should vigorously develop data assetisation, applying different types of data assets to specific use cases to unlock data dividends. This approach supports the scientific development of corporate investment decisions and enhances investment efficiency.