Mario, 27, said it was "time to move on" as he explained the show has given him "many opportunities" over the years.
Now, some of Mario's co-stars have taken to Twitter to react to his exit.
James 'Arg' Argent said: "You will be missed mate. Good luck for the future & I wish you all the best! You've been a big part of #TOWIE #TheOnlyWayIsUp @Mario_Falcone."
Arg's girlfriend, Lydia Bright, tweeted: "Sad to hear that @Mario_Falcone after four years is leaving #TOWIE. Wishing you all the best in the future, you will be missed."
Lydia's mum, Debbie Douglas, wrote: "Wishing you all the happiness in the world @Mario_Falcone I will miss you sooooooooooo much my Italian Stallion. #bigbighugs."
Pete Wicks said: "Sad to see the big man leave but wishing you all the luck in the world @Mario_Falcone #TOWIE."
The official TOWIE Twitter account even got in on the action, saying: "Last scene to his first, today we say goodbye to Italian stallion, @mario_falcone, who leaves #TOWIE after 4 years."
From his original relationship and engagement to Lucy Mecklenburgh, to his feud with Mark Wright, and plenty of naked scenes, Mario has been involved in some of the show's major storylines since joining in 2011.
He has also been involved in romances with Chloe Sims and Lauren Pope, and in August 2013, he even stepped away from Essex to go into the Celebrity Big Brother house.
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