The dancer was dropped from the celebrity competition in the upcoming series but had been announced as one of the professionals taking part in a new 'dance group' segment.
Instead, he will focus on the stage show Burn The Floor, which he stars in with girlfriend and former Strictly partner, Ali Bastian.
Fortuna said: "I really enjoyed working on Strictly over the years - loved the fans and loved all the people I got work with - but there are changes planned for the next season so I've decided not to return to the show.
"Both Ali and I are looking forward to seeing all our fans at the Shaftesbury Theatre."
Other professional dancers from the last series who will no longer be involved as partners to the celebrities are Darren Bennett, Lilia Kopylova, Ian Waite and Matthew Cutler.
Fortuna won the 2009 Christmas special of Strictly with Bastian.