PurposeBased on the social exchange theory, the aim of the present study is to examine the effects, both direct and indirect (through sustainability-oriented innovative behaviors [SIBs]), of sustainable project leadership (SPL) on sustainable project performance (SPP). Project management approaches (PMAs) (traditional, hybrid and agile) were examined as conditional factors in the “SPL–SIBs” relationship.Design/methodology/approachThe study employs structural equation modeling based on data collected from 197 software engineering project team members working in the financial industry in Poland.FindingsThe study revealed that SPL significantly, positively affected SPP. It also provided evidence for the significant mediating impact of SIBs in the relationship between SPL and SPP and the conditional effect of agile and hybrid PMAs on the “SPL–SIBs” relationship.Originality/valueThe novelty of this work lies in introducing sustainable leadership into project management research, proposing and testing a unique and complex research framework, designing valid scales for measuring SPL and SPP, and suggesting many theoretical and empirical implications.