The pop star and her security team turned up at Ashton's house in Los Angeles at around midnight, a photographer told TMZ.
We never put these two down as close buddies, so we've been left scratching our heads.
It could well be RiRi is looking for a new pad, as Ashton's $10million place might be on the market.
Justin Bieber apparently checked it out recently with a view to buying the property.
[Related article: Rihanna even makes food shopping look cool]
[Related article: The Wanted get Punk'd by Ashton Kutcher ]
However, we don't know many people who go house hunting in the middle of the night.
The actor and singer have both been in the press a lot for their relationships with their exes, Demi Moore and Chris Brown, so they have that in common.
Maybe the 24-year-old singer was interested to hear all about Ashton's latest adventure.
The Two and a Half Men star will become the 500th person to take a voyage on Virgin Galactic.
We admit, we're very intrigued.