Kim Kardashian Shows Underboob During London Birthday Celebrations

Kim Kardashian’s birthday bash is turning into a marathon of jaw-dropping looks ... and in London, she cranked it up ... serving some serious skin all night long!

The multi-talented mogul hit up photog Mert Alas’ London pad Wednesday night for her 45th birthday blowout ... rocking a corset-style ensemble that served major underboob ... all while dripping in bedazzled details that were most definitely OTT.

Kim later switched into another corset-style ensemble, this time white and sheer ... and TBH it was a risky choice ... especially in those chilly London temps. One wrong move in those outfits, and we’re talking full-on nipple slip territory.

But Kim wasn’t fazed one bit -- oozing body confidence as she hit the after-party for the London premiere of her new Hulu legal drama, "All’s Fair"... this time in a look that was a bit more covered up.