Eco-innovation has turned into the hotspot of numerous enterprises and governments to gain sustainable development. This study examines how enterprises acquire green knowledge in interorganizational cooperative eco-innovations, exploring the influence of different collaborative modes and the direct and moderating roles of specific investments. In accordance with interorganizational interaction level, the widely used collaborative modes can be attributed to low-(e.g., commissioned research and development [R&D]), medium-, and high-interaction modes (e.g., joint R&D and co-construction of R&D entities). Results from a survey of 172 Chinese firms operating in the new energy vehicle industrial chain support that both specific investments and collaborative eco-innovation have positive effects on green knowledge acquisition. Furthermore, the positive effect of collaborative eco-innovation is stronger for high-interaction collaboration modes than that for low-interaction collaboration modes. Specific investments also play a moderate role in the link of collaborative eco-innovation and green knowledge acquisition; similarly, the positive moderating effect is stronger for high-interaction collaboration modes than that for low-interaction collaboration modes. These findings suggest that when managers formulate the environmental policy, they should encourage collaboration, interorganizational interactions, and specific investments to acquire green knowledge. This paper mainly contributes to open eco-innovation literature by revealing the mechanisms and the boundary conditions under which collaborative mode could effectively promote green knowledge acquisition.