The singers were spotted sitting side-by-side at Giorgio Baldi in Santa Monica—a restaurant that both frequent separately whenever they're in town.
RiRi, who was conservatively dressed for the outing in black skinny jeans and a matching sweater, was seen laughing and smiling throughout the meal.
She left in a chauffeured vehicle, while the Coldplay frontman left in his car through the private back exit.
But let's not rush to conclusions about their dinner, even though the stars are both technically single.
RiRi and Martin have known each other for years and even collaborated on Coldplay's 2011 hit "Princess of China."
Devone Byrd, PacificCoastNews
The evening get-together came just hours after Martin was seen grabbing brunch with his ex, Gwyneth Paltrow, and their two children, Apple and Moses.
The family enjoyed brunch at Malibu Farm with a few friends and all seemed to be in happy spirits throughout the meal.
The Oscar-winning actress sat next to Martin and showed off several photographs on her iPhone to the table.
Martin and Paltrow have been spotted together in the recent months, proving that they may just be the friendliest exes in Hollywood.
The duo announced back in March that they were "consciously uncoupling" after more than ten years of marriage.
"It is with hearts full of sadness that we have decided to separate. We have been working hard for well over a year…to see what might have been possible between us, and we have come to the conclusion that while we love each other very much we will remain separate," they announced in a joint statement on Paltrow's website, Goop.
"We are, however, and always will be a family, and in many ways we are closer than we have ever been."