<p>Employees who experience stagnation in their formal employment may not always find sufficient opportunities for regular job crafting within their primary job. In the context of the growing gig economy, we aim to expand the boundary of job crafting beyond traditional organizational roles to include the gig domain. We introduce gig-based crafting, defined as full-time employees’ proactive and intentional efforts to shape their side hustles in alignment with their personal strengths and interests. Drawing on conservation of resources theory, we empirically explore whether this practice of crafting affects employees’ in-role performance and extra-role citizenship behaviors in their full-time jobs. Data from a three-wave survey of 298 full-time employees with side hustles indicated that gig-based crafting was positively related to employees’ job performance and citizenship behaviors in their formal jobs. This relationship is mediated by role-breadth self-efficacy and positive affect, representing cognitive and affective mechanisms, respectively. Theoretical and practical implications for employees’ crafting of work lives in the gig economy are discussed.</p>