Osbourne, 29, has had a bumble bee tattoo as a tribute to her friend, who passed away at the age of 81 last month, reported Femalefirst.
"In honour of you @joanrivers... 'If you looked at aerodynamics, at science, the bumble bee should not be able to fly. Physically, it was just not anatomically equipped to soar. Yet it did, defying gravity, defying logic. The bee was a creature that defied and beat the odds, a miracle'. Thank you for being my Miracle@joanrivers. (sic)," she wrote along with picture of her tattoo.
Rivers passed away in September after complications with throat surgery, which left her in a coma.
Osbourne and Rivers worked together on the hit TV show and Osbourne had recently revealed that she is keen to adopt Rivers' dog.