Vice-chancellor Harlene Hayne said Prof Ballantyne was ''well-placed to take the helm'' of humanities.
''At a time when the value of the humanities is constantly being questioned, Prof Ballantyne is the ideal person to remind New Zealand about the cultural, civic and economic value of ... humanities.''
Prof Ballantyne, who worked previously at the National University of Ireland, Washington University in St Louis, and the University of Illinois, has been the head of Otago's history and art history department since 2012.
His research has centred on the 19th-century British empire.
Prof Ballantyne said he was ''very excited'' about taking on the role, and committed to casting a wide net with the division's community engagement.
''I am also committed to extending the division's links beyond the university, to schools, professional bodies, government, the business sector, iwi - especially Ngai Tahu Whanui - to our city of Dunedin, the wider Otago and Southland region, and beyond.''
Prof Ballantyne will start his new role in October, succeeding Brian Moloughney.
Prof Moloughney was stepping down after five years in the role, a university press release said.
