Deceuninck - Quick-Step sprinter Cavendish will make his Tour comeback after three years away from the race, as Deceuninck's chosen sprinter Sam Bennett is forced to miss the race due to injury.
After dealing with illness, injury and disruptive team changes in recent seasons Cavendish, 36, is back on form this year as he is racing on a one-year contract with Patrick Lefevere's team in 2021.
The Manxman will be racing the Tour alongside reigning world champion Julian Alaphilippe.
Cavendish, who last raced the Tour in 2018 in Dimension Data colours, said: "I am delighted to be going back to the Tour de France with Deceuninck – Quick-Step.
"Obviously, the circumstances with Sam could be better – he had a special Tour last year and I am sad for him not being able to defend his green jersey.
"But at the same time, I am excited to be going back to a race that I have such an affinity with and where I have so much history. It is the biggest bike race in the world, and I am going to do all I can to grab this opportunity with both hands."
After winning four stages in the 2016 Tour Cavendish fell ill with Epstein-Barr virus in 2017, which marked the start of a turbulent few years for the 'Manx Missile'.
Cavendish struggled to return to form, winning no races from 2018 until early in 2021, as he also race one unsuccessful season with Bahrain-McLaren in 2020.
But after rejoining Lefevere's Quick-Step team at the start of 2021, Cavendish has been back on the top step five times already this year, including winning four of the eight stages in the Tour of Turkey.
Cavendish was not expected to race the 2021 Tour de France as Deceuninck were likely to back their main sprinter Sam Bennett, winner of the green jersey in last year's race.
Bennett then suffered a knee injury while training earlier this month, raising the possibility that Cavendish could step in for the Irishman at the Tour.
Despite team boss Lefevere's suggestion to the contrary, Cavendish will now step in for Bennett.
Bennett said: "Needless to say, I’m very disappointed to not be able to defend my green jersey at this year’s Tour de France.
"I had a very minor incident during training a couple of weeks ago, which effected my knee. While the injury I sustained is very short-term, it impacted my training for the biggest bike race in the world all too much and left me without enough time to be race fit.
"Le Tour deserves me at my best and it would do my team, and myself, an injustice to race in my current condition. I wish the whole Wolfpack a successful three weeks on the roads of France."
While Cavendish will target the sprints, Julian Alaphilippe will be chasing more glory in his home Grand Tour, having won multiple stages and worn the yellow jersey in the last two editions.
Alongside the two star riders, Deceuninck will take Kasper Asgreen, Davide Ballerini, Mattia Cattaneo, Tim Declerq, Dries Devenyns and Michael Mørkøv.
Sports director Tom Steels said: "Our team is a balanced one. Julian came well out of the Tour de Suisse and the opening weekend suits him, so we’ll support him in his quest for a stage victory. Mark returns to the Tour, and it’s great to have someone with his history and experience on the team.
"He will have a superb lead-out with Ballerini and Mørkøv, and the plan is to take it day by day and see how things go. Kasper will also be one to watch, as there are a couple of stages where he can go in the breakaway, without mentioning the two individual time trials, where he can do something nice.
"Tim is one of the best helpers in the peloton, while Mattia and Dries will help Julian in the mountains and on the uphill finishes. We are confident and hopeful for a good three weeks”
Deceuninck - Quick-Step squad for the Tour de France 2021
Julian Alaphilippe (FRA)
Kasper Asgreen (DEN)
Davide Ballerini (ITA)
Mattia Cattaneo (ITA)
Mark Cavendish (GBR)
Tim Declercq (BEL)
Dries Devenyns (BEL)
Michael Mørkøv (DEN)
Wilfried Peeters (BEL)
Tom Steels (BEL)
Rik van Slycke (BEL)
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