SummaryDespite an extensive body of research on job crafting, our understanding of how bottom‐up job crafting behaviors interact with top‐down job design in influencing employee effectiveness remains limited. Drawing on conservation of resources theory, we developed and tested a theoretical framework to examine the implications of daily promotion‐ versus prevention‐oriented relational job crafting on employees' energy and subsequent task performance, in the context of relational job design (i.e., task interdependence). To test our theorizing, we conducted two experience‐sampling studies over 10 workdays with full‐time employees across various organizations (Study 1: Nday‐level = 845, Nperson‐level = 126; Study 2: Nday‐level = 793, Nperson‐level = 108). Multilevel path modeling indicated promotion‐oriented relational job crafting was positively associated with subsequent task performance by increasing energy levels (Study 2), particularly when task interdependence was low (Study 1). In contrast, prevention‐oriented relational job crafting was energy depleting in low‐task‐interdependent contexts (Study 2) but increased employees' energy in high‐task‐interdependent contexts (Study 1). Our findings suggest different forms of day‐to‐day relational job crafting behaviors are relevant for employees' energy and performance, but their effectiveness may depend on the relational job‐design context.