Three vapor chambers with biomimetic leaf vein wick structures were fabricated through laser processing, assembly, working fluid charging, and encapsulation processes. A thermal performance evaluation system was established to simulate practical chip cooling scenarios. Comprehensive tests were conducted on the startup behavior and steady-state heat transfer characteristics. These tests demonstrated the performance advantages of the leaf vein-inspired vapor chambers in both the dynamic startup and stable heat transfer phases. The influence of filling ratios on operational stability was systematically investigated. Two customized thermal management test platforms for electronic devices were developed to validate the optimized vapor chambers’ effectiveness under practical working conditions. Experimental results confirmed the superior heat dissipation capability of the bio-inspired structure across various thermal loads. However, like any research, this study has certain limitations. This research provides an innovative thermal management solution for high-power electronic devices operating under extreme thermal conditions, and also points out potential directions for future research.