British model Alexa Chung and musician, Rita Ora, were among the famous guests present in Harry Styles' birthday party. The One Direction singer turned 21 this February 1 with a birthday bash in Los Angeles. The party was a star-studded event that included other celebrity guests such as David Beckham, Cara Delevingne and Kendall Jenner.

Harry and girlfriend, Nadine Leopold sang the night away in karaoke during the party. An insider has told The Sun via an article published in The Mirror UK that Harry and Nadine seem to be crazy about each other, saying:

"Everyone's teasing him, saying he's in love, and he's not denying it. It's the real deal.

"He's never felt this way about anyone before.

"Harry has spent virtually all his free time in Los Angeles with Nadine. They're infatuated with each other and can't stand being apart.

"There's nobody else he'd rather be with on his birthday."

Cupcakes completed the milestone event in the One Direction's singer at the Lulu's Cafe near Hollywood. There were even some fans outside the eatery that got some of the cupcakes from their idol's birthday party, too! These fans gladly appreciated their idol's sweet gesture on his special day.

In an article published in Heat World, it was revealed that the other guests in attendance for Styles' birthday bash included supermodel Cindy Crawford and singers Adele and Chris Martin. People reported that Maroon 5 singer, Adam Levine, actress Courtney Cox and Rashida Jones celebrated their One Direction friend's birthday on Sunday, as well.

People magazine reported that Harry received four cakes from his mother, Sweet Lady Jane.

An insider revealed that, "When he blew out his birthday candles, he FaceTimed his mom."

"He was so sweet to all his guests."

We wish Harry Styles a very happy 21st birthday. He sure had a lot of fun celebrating the big day with his friends and loved ones!