Tomasel, from Queensland, has come from several years of radio host duties in Australia,
and is a social media star with 26,000 Instagram followers - including Channing Tatum.
She also once posed as a member of Gloriavale.
Roberts, from Rotorua, lives in West Auckland and has worked at The Edge and George FM.
Ross Flahive, Content Director for ZM, is looking forward to getting them on air.
"Bree and Clint are both incredibly talented in their own rights, and make for great radio when they're together," he said.
They replace the current Drive Show, hosted by Jase and PJ from Australia. They're staying with ZM.
Jase and PJ will be staying with ZM, and details of their new show will be announced shortly.
Tomasel and Roberts' first day on air is July 2.