The couple were seen walking hand-in-hand as they made their way to the celebrations, which was being held at Bar Blanca in Soho, London.
Series 14 came to an end almost three weeks ago, but the cast only just got round to celebrating it on Wednesday night (22 April). Better late than never!
Fran looked chic in a cute embellished white shift dress and heels alongside Diags, who looked smart in a navy blazer.
In March, Fran marked a full year on the show, where she told fans she was grateful to be casted as it bought her and Diags together - and they're still going strong!
Fran said at the time: "Wow a whole year since I've been with @OnlyWayIsEssex, what a crazy one but, if it wasn't for TOWIE, I wouldn't have been with my soulmate."
During the series finale, Fran made a cute Alice in Wonderland at James 'Arg' Argent's Mad Hatter-themed tea party. While Fran looked pretty as Alice, Diags kept his face covered up as the White Rabbit!
For exclusive competitions and amazing prizes visit Reveal's Facebook page NOW!
Behind the scenes at the Mad Hatter tea party:
Copyright: Twitter @Mario_Falcone
TOWIE's most shocking moments: