Gwen Stefani and Blake Shelton -- We're Dating!!!

Blake Shelton and Gwen Stefani are dating ... TMZ has confirmed.

A rep for Gwen tells TMZ they wanted to reveal the new relationship Wednesday night as they celebrate the CMAs in Nashville.

We're told Gwen and Blake will be attending several after-parties following the awards ceremony.

Our sources say Gwen made the decision at the last minute to fly to Nashville with Blake. We're told her plan is to go to the after-parties but not the CMAs. We asked if it was because Miranda Lambert was going to be there and one source said, "She doesn't care if Miranda's there or not. She just didn't have the right clothes for the award ceremony because it was so last minute."

They will not be hiding their relationship tonight. We're told they'll spend a few days together in Nashville.

As for how long they've been dating ... we're told "just days."

5:14 PM PT -- As we told you, Blake's flying solo at the CMAs. Expect plenty of cutaways to his seat.