Liam and Sophia were among the stars invited to the bash hosted by Instagram's Kevin Systrom and chef Jamie Oliver.
Sophia looked glamorous in coated black jeans, a black blazer and nude heels. The brunette was all smiles as she cuddled up to Liam for a photo. Meanwhile, Liam looked smart in black jeans and a dark denim shirt.
Liam and Sophia, who began dating last year, are childhood friends having attended the same school in Wolverhampton.
They were joined at the party by boyband Blue and TOWIE's Lauren Pope. This is Kevin and Jamie's second annual private party, which took place at Jamie's restaurant Barbecoa.
Last week, 1D arrived back in London following their world tour in Tokyo. Zayn Malik and Louis Tomlinson were spotted back on UK shores separately from remaining bandmates, Liam, Harry Styles and Niall Horan.
For exclusive competitions and amazing prizes visit Reveal's Facebook page NOW!
Watch One Direction's video for 'Night Changes' below: