Tajer will pass over the reigns to Baxter on 1 December when he steps in full time as executive chairman of Mediabrands to focus on the growth and expansion of the IPG agency's local footprint.
Baxter is currently chief strategy officer of MediaCom Australia and former founding partner and CEO Asia-Pacific of Naked Communications.
"Mediabrands is a way for us to provide clients with a full array of resources in communications planning, implementation and measurement," said Tajer. "To do this well our key companies need the highest calibre of leadership and talent. Mat's decision to join UM as CEO is testament to the strength of our vision and a huge endorsement for UM and Mediabrands' plans for the future."
"I'm enormously excited about joining UM," said Baxter. "UM was one of the few agencies I genuinely feared competing with in my previous roles. They've got a hugely impressive track record and an even more impressive client list. They're undoubtedly Australia's most creative communications agency. I'm absolutely thrilled to be their new CEO."
Tajer said that Baxter's experience and clear vision for how media can be leveraged for clients was a key fit for UM Australia. Baxter's arrival at UM will be the second time he and Tajer have worked together – the pair met at Zenith Media about eight years ago.
Baxter commented, "UM is an agency with great momentum. It has amazingly strong client relationships and is renowned as one of the best collaborators with media owners. I hope to build on that success even more and carve out a position for us at the very top of the media agency table."
With Baxter's appointment, Tajer will focus on broadening Mediabrands' Australian operations. In addition to existing communications skills, the group will develop greater capabilities for clients in social media platforms and other communications channels.
"Mat's arrival frees me up to take a more holistic approach to growing our local business. Now I will have the time I need to dedicate to the development of Mediabrands here in Australia," said Tajer.