Industry–education integration in vocational undergraduate education has long remained at a shallow level such as “contractual cooperation” and “order-based training”, and the structural contradictions of “enthusiastic schools and cold enterprises” and “cooperation without depth” have not been substantially alleviated by the growth in the number of communities. The crux of the problem does not lie in the absence of willingness to cooperate, but in the failure of the relational structure of cooperation to undergo a qualitative change: the school-enterprise relationship is still an “additive relationship” in the sense of resource exchange, rather than a “symbiotic relationship” in the sense of mutual embedding of competencies. Taking symbiosis theory as its analytical framework and drawing on the recent practices of institutions such as Nanjing University of Industry Technology and Henan Polytechnic Institute, this paper proposes that moving industry–education integration in vocational undergraduate education from “cooperation” to “symbiosis” requires the completion of a threefold mechanism transformation: in terms of the motivational mechanism, a shift from emotional drive and administrative push to the endogenous production of interests, so that enterprises obtain a sustainable reason to participate through the formulation of community rules, resource investment and benefit sharing; in terms of the governance mechanism, a shift from loose liaison to substantivized operation and the separation of powers and responsibilities, using council-based decision-making, a points-based management system and a flexible teaching–production coordination system to transform “joint cultivation of talent” from an intention into operable rules; and in terms of the knowledge mechanism, a shift from one-way resource extraction to the two-way transformation of technology and teaching, so that enterprises’ real technical problems become the living source for curriculum and teaching renewal. The convergence point of the three mechanisms is that vocational undergraduate institutions transform from “resource consumers” into “competency producers”, thereby forming an irreplaceable symbiotic value in the industry–education relationship.