Little Mix are the toast of the US, after their second album Salute topped the American iTunes charts within a day of its release.
"I have just been told that the new Little Mix album is number one on the US iTunes album chart. That is bloody fantastic. Congratulations," he wrote.
One Direction's Niall Horan added: "The lovely girls of @LittleMixOffic have are at #1 on the iTunes chart, you guys gotta keep it there for the week! It's a great album!"
Salute, the follow-up to their debut DNA, was released in America on February 4 and beat Bruno Mars' latest album, Unorthodox Jukebox, to the top spot.
The album, which includes singles such as Move and Little Me, peaked at number four in the UK when it was released last November.
Jesy tweeted: "Oh my flipping gooddd!!!! Can't believe were no1 on iTunes keep supporting the album mixers love u x Jesy."
The girl group's first album, DNA, reached number four on the Billboard charts last year.