Bass will report to Tajer, who served as global COO and CEO of Australia operations until his promotion to global CEO, which was announced in March.
The company offered the position to Bass after a search across Australia and international markets, the agency said.
Bass's start date in the CEO chair has yet to be confirmed, but when he takes over, Tajer will become chairman of Australia operations. Bass has also served in the past as GroupM’s chief digital officer and national sales director for News Digital Media.
Last week, IPG Mediabrands named Reg Davidson chief operating officer of IPG Mediabrands Australia.
“Danny Bass became a clear choice as the ideal leader for the 600 plus people who work in the Australia group, our skill sets, client relationships and valuable external partnerships,” Tajer said in a press release. “He is a future-facing, highly effective leader who is a perfect fit for the way we progress as a business and work as a national team.”
Australia is IPG Mediabrands' second-largest business worldwide.
Update, 2 pm: GroupM has appointed Sebastian Rennie, MEC chief investment officer, as GroupM chief investment officer, replacing Bass.
Rennie has over more than 15 years of media experience in the UK and Australia. He joined MEC in 2008.
“Seb is one of our brightest talents and is widely respected in the market by both media owners, clients and competitors," John Steedman, GroupM Australia chairman and CEO, said in a release.
MEC will announce a replacement for Rennie in due course, it said.