The synergistic development of digitalization and greenization is an inherent demand for high-quality economic and social development. Whether enterprises can use digital transformation to realize green transformation and upgrading has become an important strategy for enterprises to obtain sustainable competitive advantages in the new competitive environment. In light of the practice of Inspur’s green development, this article systematically explores the process of green innovation and the impact mechanism of digital transformation on green innovation through a longitudinal case study. Our findings reveal that: (1) The impact mechanism of digital transformation on green innovation is manifested in digital management technology empowerment and digital-green synergy and business deep cultivation, behind which is the role of digital transformation on the allocation of resources and the combination of resource relations. (2) The development of green innovation based on digital transformation embodies a development logic of niche change. The expansion of resource space, the enhancement of capacity and the maintenance of dynamic balance of the system are all realized through niche transition and niche movement. (3) The green innovation process based on digital transformation benefits from the context of executives’ green cognition, and the proactive and responsible innovation behaviors tend to support the implementation of green innovation activities. The research findings provide new attempts and explorations for the mining of relevant theories.