The pair were first romantically linked after they released their duet 'Almost is Never Enough' in August and at the time, the pair dodged questions about a blossoming romance.
But Nathan broke his silence on Twitter last night (24 September) following recent pictures of the pair at Disneyland, in which they were seen cuddling and holding hands.
He said: "So, I guess it's obvious now … Thanks to everyone who is being so lovely. I'm so happy #butweareterrified #pleasedontkillme #orariana."
Meanwhile, Ariana, who is most famous for her role as Cat Valentine in Nickelodeon's Victorious, retweeted Nathan's message and added: "We hesitated saying anything as people can be a bit insensitive but thank you, we value all of your happiness, thank you for valuing ours."
And Nathan's bandmate, Max George, has already given his consent. He said: "@NathanTheWanted @ArianaGrande very happy for you little brother. She's a sweetheart."
It was only last week that Ariana dismissed the pair were an item when she told Access Hollywood: "No, no, we're not dating," but she did gush about her new boyfriend, saying: "He's the sweetest. He's amazing."
We think these two make such a cute couple!
Watch Ariana's video for 'Almost is Never Enough' below: