Purpose:　Organizational　citizenship　behaviors　for　the　environment　(OCBEs)　represent　a　crucial　element　of　environmental　sustainability　for　a　wide　range　of　organizations.　However,　the　leadership　mechanisms　underlying　OCBEs　are　as　yet　unexplored,　particularly　regarding　the　delivering　megaprojects.　The　paper　aims　to　investigate　how　transformational　leadership　(TFL)　and　transactional　leadership　(TSL)　styles　shape　the　environmental　commitment　(EC)　of　subordinates,　motivating　OCBEs　in　megaprojects.　Design/methodology/approach:　Partial　least　squares　modeling　and　hierarchical　regression　were　performed　on　data　obtained　from　140　experts　who　have　been　involved　in　megaprojects.　Findings:　Both　TFL　and　TSL　styles　are　effective　in　motivating　OCBEs,　although　the　EC　of　subordinates　partially　mediates　these　relationships.　The　power　distance　(PD)　orientation　significantly　moderates　the　relationship　between　TFL　and　OCBEs,　with　the　relationship　being　more　positive　when　the　PD　of　subordinates　is　lower.　Unexpectedly,　a　collectivist　orientation　(CO)　was　found　to　elevate　the　effect　of　TSL　but　weaken　the　effect　of　TFL.　Originality/value:　The　mixed　and　contradictory　findings　regarding　TFL　and　TSL　styles　are　reconciled　in　the　current　study　by　integrating　the　contextual　factors　of　PD　and　CO.　The　findings　of　the　study　shed　new　light　on　“playing　the　cards　right”　when　using　the　leadership　practices,　i.e.　how　leadership　can　be　better　leveraged　to　cultivate　subordinates＇　OCBEs.　They　also　provide　targeted　guidance　for　shaping　contextual　factors　to　increase　the　environmental　sustainability　of　megaprojects.　©　2021,　Emerald　Publishing　Limited.