The Keeping Up With The Kardashians star was among the fans who attended Rihanna's concert in Anaheim on Wednesday night.
Writing on her Twitter account after the show, the reality star praised both Rihanna and her fanbase: "Had so much fun at the #LoudTour! Amazing performance by @rihanna you won't want to miss that sexy kitty! #RihannasNavy was in full effect (sic)."
Kardashian also had words of praise for the popstar's cover of 'Darling Nikki' by Prince, writing: "I love that @rihanna sang "Darling Nikki" and KILLED it! Not many people can sing a prince song and rock it #Leggo."
Rihanna later tweeted a message to Kardashian and her brother Rob, saying it had been fun to catch up with them backstage: " Khloé and Rob So good seeing u guys backstage tonight!!! You f""kin rock!!!"
Kardashian responded: "Die for you baby! Kill the rest of ur tour!"
This is not the first time Kardashian and Rihanna have exchanged tweets. Back in March, Kardashian described the singer as a "goddess".
"From one goddess to another... Keep on shining! Everyone one loves watching! LOL :) keep showing them what you got!" she wrote, prompting Rihanna to respond: "Just when I thought I couldn't love u anymore.... thank u."
Rihanna, who has described Kardashian and her husband Lamar Odom as "too cute for words", later engaged in some Twitter flirtation with Kardashian's brother Rob, who suggested Rihanna could be his date for sister Kim's wedding.
Rihanna will play the Oracle Arena in Oakland, CA tonight.
Watch Rihanna's music video for 'Only Girl (In The World)' below: