Answer by taking a quote from the following article:

Kyle Dalton Sandilands (born 10 June 1971) is an Australian radio host living in Sydney. He is currently the co-host, with Jacqueline Henderson, better known as Jackie O, of the weekday morning radio program The Kyle and Jackie O Show on Sydney's radio station KIIS 106.5. From 2005 to 2009, Sandilands served as a judge on Australian Idol. In 2008, he became the host of Big Brother, alongside Jackie O.

Sandilands landed his first radio job in 1992, at age 21, at 4TO Townsville where he was employed to drive the station's promotional vehicle. Within weeks he had declared his willingness to do whatever it took to get ahead: to work anywhere, in any time slot. He took gigs in Cairns, and then Darwin, before joining Austereo's Triple M in a Brisbane station by using a false resume to impress one of the station's executives. In 1999, he moved to Sydney, and commenced at 2Day FM as host of the Hot30 Countdown, replacing "Ugly Phil O'Neil", a former husband of Henderson (Jackie O). Sandilands attributes his radio career taking off to being told by then Group Program Director Jeff Allis to "do whatever you want, just win". Sandilands revealed he was paid $255,000 per year while working on the Hot30.  Much media coverage of Sandilands has focused on the negative aspects of his personality and behaviour, notably his widely publicised clashes with and criticism of other media figures, his intemperate on-air outbursts and his alleged "out of control" ego. In September 2006, Sandilands was named the most hated Australian identity in a Zoo Weekly article, although on 14 October 2006, Sandilands and Henderson were named "Best On-Air Team" at the Australian Commercial Radio Awards. Sandilands and Jackie O were again named "Best On-Air Team" at the Australian Commercial Radio Awards in 2007, 2011, and 2015.  In August 2009, The Kyle and Jackie O Show was put into "indefinite recess" by the Austereo network as a result of a controversial on-air stunt on his morning show on 29 July 2009. He returned to his radio show on 18 August 2009 but was suspended on 9 September 2009 due to on-air comments relating to Magda Szubanski. In the same year he was again named the most hated by Zoo Weekly. Sandilands and Henderson were the hosts of the nationally syndicated chart show The Hot Hits, before swapping host roles with Andrew Gunsberg in December 2009, who had previously hosted Take40 Australia, but left the show at the end of 2011.

What did Sandilands do on the radio?
In 1999, he moved to Sydney, and commenced at 2Day FM as host of the Hot30 Countdown, replacing "Ugly Phil O'Neil", a former husband of Henderson (Jackie O).