Purpose – The purpose of this paper is to investigate the roles of online leadership in opencollaborative innovation success by extending functional leadership theory in the context of open source projects. Design/methodology/approach – This study uses negative binomial regression models to empirically test the proposed hypotheses with samples of blockchain open source projects on GitHub. Findings – The results indicate that task-oriented leadership behaviors in forms of technical contributionshave little influence on open collaborative innovation success; relation-oriented leadership behaviorsembedded in internal social capital and external social capital contribute to open collaborative innovation success prominently.Furthermore, the joint effects of technical contributions, internal social capital andcommunity commitment with openness orientationare positively significant on open collaborative innovationsuccess, respectively.Practical implications – For leaders and participants of open collaborative innovation projects, they should attach importance to both leadership behaviors and the joint effects with openness orientation so as to make informed decisions.Originality/value – This study offers a new fine-grained framework of open collaborative innovation success by investigating specific dimensions of task-oriented and relation-orientated leadership behaviors, as well as their joint effects with openness orientation.