The accolade comes from Sir Bradley Wiggins who also said the Manx-born cyclist was the "greatest sprinter".
Sir Bradley became the first UK rider to win the Tour de France in 2012.
His comments come ahead of a major cycling event on Sunday when Cav will attempt to break a Tour de France world record set 46-years ago.
Mark Cavendish has already won four stages at this year's tour, meaning he's currently level with Eddy Merckx on 34 wins.
There are two sprints still to contest so it's possible Cav could eclipse the Belgian rider and rewrite the history books
To celebrate, the Manx government's arranged a fan zone showing live Tour, big screen coverage.
Everyone's invited to attend the Villa Marina Gardens from 2pm, the government says there'll also be food and drink stalls.