The aim of this study was to investigate the existence of collaboration-based business model innovation through an open innovation strategy among multigenerational-cohort SMEs in the context of the Thailand setting. This current research identified four key antecedents of open innovation based on resource and capability review. Open innovation is examined in two main strategies: (1) open innovation breadth and depth, and (2) open innovation cooperation. Using survey data from family-owned SMEs in Thailand, we estimate multigroup structural invariance models considering four generational cohorts by age: Generation Z, Generation Y, Generation X, and Baby Boomers. The empirical results indicated that family business owners are more likely to pay attention to innovative human capital and strategic agility among Generation Y and Baby Boomers. Meanwhile, Generation Z, Generation Y, and Baby Boomers tend to understand the importance of strategic agility before they strategize their breadth and depth of open innovation. To execute an open innovation strategy, Generation Z, Generation Y, and Generation X tend to implement a partner-search strategy and then do a cooperation plan. Our findings imply that business practitioners should understand the moderating role of generational cohorts due to their experience age. There are differences among Generation Z, Generation Y, and Generation X when participating in collaboration-based business model innovation using an open innovation strategy.