With the rise of the post-Schumpeterian innovation paradigm, manufacturer-user (MU) collaborative innovation has become a crucial means of promoting technological innovation and achievement transformation. A theoretical framework for MU collaborative innovation was constructed by reviewing the theoretical underpinnings of MU collaborative innovation and clarifying the distinctions between MU collaborative innovation and single-subject innovation. A theoretical framework encompassing roles, modes, processes, mechanisms, and commercialization of MU collaborative innovation was proposed. MU collaborative roles and modes are identified as drivers of the MU collaborative innovation process, with manufacturers and users taking on different roles and utilizing distinct modes in the collaborative innovation process. A MU collaborative mechanism was constructed from the four perspectives of strategy, knowledge, organization, and digital technology. MU collaborative commercialization was explored in terms of heterogeneous commercialization needs, opportunities for use and verification, and the initial adoption and diffusion of innovative achievements. Three future research directions are proposed: user-led MU collaborative innovation, AI-empowered MU collaborative innovation, and MU collaborative innovation in ecosystem contexts. New perspectives and insights are provided for academia and industry through the construction of the theoretical framework of MU collaborative innovation and the proposal of future research directions.