The 30-year-old Australian sprinter posted two wins in the Tour of Taiwan and 18 top-10 finishes including a sixth in a bunch gallop to the line in stage four of the Tour de France.
Cantwell turned professional in 2008, riding for the Jittery Joe's and Fly V Australia teams, before joining Bjarne Riis' squad this year.
Cantwell said: "In many ways 2012 was a testing year for me trying to establish myself at World Tour level after some years of riding primarily in the States.
"I think I did pretty well, got a few victories and quite a lot of top-tens, and I was part of our line-up for the Tour de France. But I'm also confident 2013 can be a much bigger year for me.
"Now I know the races and parcours a lot better, which is a huge advantage, and I have a lot more confidence in myself. So I really look forward to the next season."
Anders Lund, who rode in the Giro d'Italia and Tour de France, has also penned a new one-year contract.
- Tour de France