Ferne dressed to impress in a fitted black leather and lace off-the-shoulder dress as she arrived at the party which was being filmed for the ITV2 reality show.
Charlie, who turns 22 today (17 March), was accompanied by sister Chloe and friends Mario Falcone and Lauren Pope to toast his birthday celebrations.
Also in attendance at the club in Essex was Tom Pearce, James 'Diags' Bennewith, Fran Parman and Jasmin Walia.
Charlie, who dressed all in black, was pictured opening a bottle of champagne as he sat down with his co-stars in the club.
The party seemed to have left Charlie in a reflective mood, as he later tweeted: "22 years old tomorrow. This is it. I'm actually going to have to behave like an adult haha."
Wishing Charlie a birthday message today, Ferne posted a photo of the pair leaving the venue together last night, in which Charlie had wrapped his arms around her.
Emphasising the word 'friend', Ferne tweeted: "Happy Birthday to a very good 'friend' of mine. Have a lovely day @charlessims_ haha he still can't leave me alone."
Are these two back on? Or are they really just friends? We're confused!
Ferne McCann (@fernemccann) March 17, 2014
Last week, viewers saw Charlie meet up with on-off girlfriend Ferne to discuss their bitter split and whether they have a future together.
Since the beginning of the new series, viewers have seen Ferne embroiled in a rather complicated love triangle with Charlie and former fling Frank Major.
Referring to Frank last week, Charlie told Ferne during their chat: "One side of me does really hate you for what you've put me through. It might sound rich coming from me, but how you could've ever fallen for that guy I'll never know.
"But the other side of me seriously does still love you, because it remembers the Ferne that I used to know."
Charlie explained to Ferne that he just wanted to be friends, but despite Ferne agreeing with his decision, the pair shared two kisses and a hug as they sat on a park bench.
But after the show, Ferne confirmed to fans that she and Charlie would remain friends. She said: "Find it so hard to let go but too much has happened...for now we are friends."
TOWIE continues on Wednesday 19 March at 10pm on ITV2.
Got an iPad or iPhone? Reveal Mag has been especially designed to fit!