Chloe and Mario were snapped as they left swanky London nightclub Funky Buddha in Mayfair.
The pals were pictured passionately kissing as they left the club before grabbing a taxi back to Essex.
Mario is close friends with Chloe’s brother, Charlie, and we wonder what he’ll have to say about their dalliance!
The TOWIE lad had tweeted a picture of his drink- a porn star martini- earlier in the evening with the caption: ‘Closest I am getting to a porn star tonight #celibacy.’
It looks like he decided to rethink his celibacy vow after a few more martinis and locked lips with his best friend’s sister.
Chloe has previously said that she would like to date someone on TOWIE.
She told a UK newspaper: ‘But for me, I’ve never had a boyfriend on the show so I might give it a go.’
Mario previously dated co-star Lucy Mecklenburgh and the couple even got engaged in Marbella.
When they split, Mario attempted to move on with TOWIE new girl Grace Andrews.
The brief flirtation fizzled out and Mario decided to give celibacy a go.
Until he decided to go on a night out with Chloe, apparently!