The 'Bad Romance' singer threw a typically lavish party at LA's No Name club on Sunday (27 March) night.
Gaga was joined on her big bight by the likes of Taylor Swift and (a very casual) Kylie Minogue, who had new fiancé Joshua Sasse on her arm as she arrived.
But they were not the only big names on the guest list, oh no.
As was Mark Ronson, who is working with Gaga on material for her upcoming fifth album - a follow-up to 2013's 'ARTPOP'.
The birthday girl herself was all smiles as she arrived at the LA nightspot hand-in-hand with fiancé Taylor Kinney.
She was wrapped up like a present in a metallic gold mini-dress with pouffy sleeves, wearing her peroxide hair up, with a rouged lip finishing off her look.
It was an early celebration for Gaga, who officially turns 30 today, and she got her birthday off to a very hungover start.
The morning after her party, she tweeted:
Gaga is currently gearing up for her big musical comeback, following highly-praised performances at the Oscars and Grammys.
As well as working with Mark Ronson on her new album, she has also reunited with producer Red One, who she collaborated with on some of her biggest hits including 'Just Dance', 'Poker Face' and 'Bad Romance'.