"After travelling with them in patches over the last two international seasons ... I'm looking forward to being fully in the NZXC environment.
"I enjoy the company of the other NZXC riders - training with them and having a great team support base at races. It's the next step to becoming professional and the best set-up in New Zealand."
Oliver will stay based in North Canterbury, but will spend time in Rotorua and travel with the team on the domestic and international race blocks during 2015.
NZXC director Sam Thompson welcomed him to the team.
"He's a great kid, obviously very talented, but humble to boot. He's a great fit with our other riders. We're really looking forward to working with him, his coach Dave Plew, and his family as he steps up the Under-23 ranks with NZXC Racing."
The NZXC Racing team now includes local riders Dirk Peters, Carl Jones, Katie O'Neill and Amber Johnston, as well as Oliver and Queenstown's Kate Fluker.