Strategic fit has long been viewed as a key factor for the successful integration of corporate ventures. Investigating sustainability ventures inside a large fossil-based chemical manufacturing firm, which are inherently at odds with the existing strategy, we found that many ventures were integrated despite strategic misfit. We identified that integration was contingent upon corporate venture managers’ ability to strategically combine strategic, structural, and environmental conditions. Our mixed-methods study, combining fsQCA and multiple-case analysis, reveals three distinct mechanisms—vanguarding, hijacking, and transmitting—that facilitate the successful integration of strategically dissonant ventures. We advance theory on strategic fit by demonstrating that strategic misfit can not only be compensated for but also leveraged for venture integration (1); disentangle the causal complexity of corporate venture integration by highlighting the interplay of contingency factors (2); and provide insights on how circular economy ventures can serve as vehicles for strategic change by offering pathways for transitioning fossil-based firms toward more sustainable practices (3).