The 'Bleeding Love' singer announced the news last night (16 April) by simply posting a photo of herself wearing a 'Def Jam recordings' waistcoat.
The signing comes as Leona held a music showcase in London this week to promote her new album I Am.
It has been revealed that the 30-year-old has inked a four-album deal with Universal Music, which houses both Island Records (who she is signed to in the UK) and Def Jam.
In June 2014, Leona parted ways with Simon Cowell's record label Syco after seven years.
Leona had been signed to Syco since winning The X Factor back in 2006, but she left the label for a new contract at Universal's Island Records.
"For my fifth album I was asked to make a record that would not be true to myself," Leona told fans in an open letter. "I'm not sure where I'll end up but one thing I am certain of is that I've stayed true to myself and I've followed what my heart says is right."
For exclusive competitions and amazing prizes visit Reveal's Facebook page NOW!
X Factor's most shocking moments: