The singers first teamed up in the studio this summer (13) to record their collaboration Almost Is Never Enough, but their chemistry spilled over into real life and they became romantically linked last month (Aug13).
They have continually denied the claims after being quizzed about the dating rumours in recent weeks, with Grande insisting earlier this month (Sep13), "No, no, we're not dating," but adding, "He's the sweetest. He's amazing. I have to say, he's one of the most talented vocalists I've ever heard in my life. And live, all the time, he's, like, spot on."
Now the young couple's secret is out after Grande and Sykes took a trip to the Disneyland themepark, where they openly kissed and cuddled - and now they've confirmed the news in separate posts on their Twitter.com pages.
Breaking the news to fans on Tuesday (24Sep13), The Wanted star Sykes admitted he was scared of his devotees' response to the budding romance, writing, "So, I guess it's obvious now... thanks to everyone who is being so lovely. I'm so happy butweareterrified pleasedontkillme (sic)".
Meanwhile, Grande has explained why they tried to keep the dating news to themselves in the early days of their courtship.
She tweeted, "we hesitated saying anything as people can be a bit insensitive but thank u (sic) we value all of your happiness, thank you for valuing ours".
Grande reportedly split from YouTube prankster/comedian Jai Brooks earlier this year (13), and Sykes was romantically linked to Amy Winehouse's goddaughter Dionne Bromfield.