Here's how Shawn Mendes celebrated his 21st birthday!

American singer Shawn Mendes who entered his 21st year on Thursday, kicked off celebrations with his rumoured girlfriend Camila Cabello and close friends at Harriet's Rooftop and Lounge at the 1 Hotel Brooklyn Bridge.

There were several beer pong tables set up that all said 'SM21' on them with matching 'SM21' pong balls. Shawn was having fun playing beer pong with his friends and had a smile on his face the entire night. Camila was by his side whole night and they looked really cute together. They took photos together and were on the beer pong table together at one point. Camila also planted a huge kiss on Shawn during the night and it was super cute," reported E!News.

Mendes was seen dancing and telling the crowd, "I'm too drunk to give a speech right now, I can't do it...I'm sorry. I love you guys."

According to an eyewitness, Shawn popped a bottle of champagne and his friends cheered for him at the end of the night. Then birthday cake was brought out for him with candles and the cake has a 'hospitality rider' theme. Camila and Shawn left together around 12:30. No one seemed too drunk or out of hand. It wasn't a wild party but Shawn looked like he had a lot of fun.

Camila Cabello posted a photo with birthday boy with a heartfelt caption."Happy birthday to this magic human, I love you!!!!" she wrote.

Hours earlier, 'Senorita' co-stars were spotted at Jack's Wife Freda in New York City around 10 a.m. for a breakfast date.