Katy Perry, John Mayer Confirm Relationship?

Katy Perry has opened up about her relationship with John Mayer at last via Twitter this holiday season.

It has been long rumored that the "Part of Me" singer and Mayer were romantically involved, but Perry's post to the social media site seemingly confirmed the relationship.

After being photographed together over Christmas in Perry's Californian hometown, the singer tweeted a picture of Mayer on Christmas Day along with the caption, "Santa Baby."

The image revealed Mayer, 35, dressed in a Santa Claus costume staring lovingly into the camera.

Perry, 28, and Mayer were first spotted together over the summer. The Twitter post marked the first time Perry acknowledged her relationship with Mayer publicly.

According to a source close to Perry, the singers' relationship is getting serious.

"They are seriously in love and exclusive," said an insider speaking to Us Weekly.

"John is surprised at just how cool and smart she is," they added. "John has proved he's matured and learned from his mistakes… Katy is blown away."

Mayer has been romantically linked to several other women in the past, including Jennifer Aniston, Taylor Swift, and Jessica Simpson, among others.

Furthermore, Mayer is reportedly growing closer to Perry's family, and vice versa. The couple was spotted in New York City with Mayer's father earlier this month while attending the Broadway show "A Christmas Carol."

"They're happier together and with her family for the holidays," said another source speaking to People. "John really likes getting to know Katy's family better. They've spent a lot of time together and really enjoy each other's company. John is entirely focused on Katy."

This Christmas is a far cry from the Christmas Perry celebrated last year. It was in December 2011 that Perry and ex-husband Russell Brand announced their divorce.