The Umbrella singer had been expected to attend the ceremony when Perry exchanged I Dos with fiancé Russell Brand.
The couple tied the knot over the weekend at the luxurious Aman-I-Khas resort in India as close family and friends watched the traditional Hindu ceremony.
Rihanna had been expected to fly into India for the three days celebrations but she was a no-show at the last minute.
Now according to US reports, Rihanna wasn't in attendance at her good pal's wedding because she had to go into the studio to record.
TMZ.com reported: 'Rihanna was a part of Katy's Las Vegas bachelorette party - but, according to our source, Rihanna told Katy she couldn't make it because she had to hit the studio.
“We're told Katy booked a special room for Rihanna - but she totally understood why RiRi couldn't hop on a plane to India.'