Research on the knowledge sharing has exploded over the past decades due to trends and integration of knowledge and talent management in modern workplace. However, knowledge hiding has been left unexplored; moreover, efforts to foster knowledge sharing remain because employees are unwilling to share their knowledge for several reasons. Drawing on psychological ownership and social exchange theory, this article investigated the nexus between perceived organizational support, psychological entitlement, knowledge hiding behavior, and extra-role behavior, and the mediating role of knowledge hiding behavior. Utilizing survey data collected from 375 employees in Jordanian commercial banks, a structural equation modeling was applied to analyze the data. Results from structural equation modeling show that (1) perceived organizational support has a positive impact on extra-role behavior, (2) knowledge hiding behavior has a negative impact on extra-role behavior, (3) psychological entitlement has a positive impact on knowledge hiding behavior, and (4) knowledge hiding behavior mediated the relationship between psychological entitlement and extra-role behavior. Implications for theory and practice are discussed.