The two arrived within minutes of each other at The Griffin nightclub on Friday, reports the New York Daily News.
Rihanna, 27, was seen getting cosy with Hamilton, 30, at the annual Crop Over carnival in Barbados, and the two spent some quality time together.
“Rihanna and Lewis had a nice little getaway last weekend in Barbados,” a source told E! News.
“Rihanna also spent time with her friends and family but Lewis was the only romantic interest on her mind. She is taking it very slow and just having fun, but she likes who he is and what he is about. There’s no label on them just yet,” the source added.
Rihana was previously linked to actor Leonardo DiCaprio while Hamilton enjoyed a long-term on-off relationship with pop singer Nicole Scherzinger.