All-time Olympic swimming great Michael Phelps announced on Twitter and Instagramearly today that he and girlfriend Nicole Johnson are engaged.

"She said yes," Phelps wrote below a photo of him and Johnson smiling in a bear hug as they rolled in the snow.

On her Instagram account, Johnson, a former Miss California USA, confirmed the engagement. "I'm gonna be a Mrs," she wrote.

It will be the first marriage for the 18-time gold medalist swimmer. Both Phelps and Johnson are 29-years-old.

The news comes as a happier episode for Phelps, who has been a staple of the gossip columns for months. In October last year, he was arrested for the second time for drink driving, and decided to enter a rehabilitation programme.

More recently, a woman who says she was born a man had claimed to have been having an affair with Phelps.

Apparently that scandal only helped strengthen his relationship with Johnson, as today's news appeared to reveal.

Following the gosspi, Phelps had taken to social media with more and more photos online of him and Johnson.