The singers' friendship fell apart when Rihanna missed Perry's wedding to now ex-husband Russell Brand in 2010.
When Perry showed her disagreement over Rihanna's patch up with singer Chris Brown, it pushed them further apart.
However, both of them seem to have put their past behind and greeted each other cheerfully at the release party for Perry's upcoming track "Prism" here, reports eonline.com.
Rihanna even posted a picture on Instagram and captioned it as: "Katy, Rihanna united."
They later went for dinner where Perry's beau John Mayer also joined them.