Born in Sri Lanka, where his father managed tea estates, Riminton briefly migrated to the United Kingdom, then to New Zealand when he was five.

In 2001, he was appointed full-time presenter of the Nine Network's national evening news program Nightline, where he remained until joining CNN in December 2004.

[citation needed] From Sri Lanka, he reported and presented during CNN's Alfred Dupont Award-winning coverage of the 2004 Boxing Day tsunami.

[citation needed] From January 2005 until September 2008, he co-anchored CNN Today with Kristie Lu Stout out of Hong Kong.

He is also an occasional guest presenter on the Network Ten's prime time alternative news programmeThe Project.

[citation needed] In 2011, he gained a second Walkley Award for his work, with reporter Matt Moran, in breaking the "Skype Scandal" in the Australian Defence Force, prompting more than half a dozen police and government inquiries.

That year the pair received awards from the United Nations Association and the Australian Human Rights Commission for their work.

actively involved in Australian Defence veterans' welfare issues and was a foundation board member of the charity Soldier On.