A picture posted on Twitter shows that the two were spotted together on Wednesday at a Jay-Z concert in the VIP section at the Brooklyn Barclays Center.
Rap Radar editor Elliott Wilson tweeted a photo with the exes taken from behind.
The singers have also been spotted kissing and dancing on Monday night.
Meanwhile, Brown announced his breakup with Karrueche Tran in a statement: “I have decided to be single to focus on my career. I love Karrueche very much but I don’t want to see her hurt over my friendship with Rihanna.”
“I’d rather be single allowing us to both be happy in our lives,” he added.
Karrueche Tran posted the cryptic message “Bye baby” on Wednesday, after Brown tweeted: “Both r Free from it all!”
Rihanna and Chris Brown were seen in NYC partying on Monday, Tuesday and Wednesday.