The 48-year-old singer and 36-year-old actor marked the occasion by treating daughter Monroe and son Moroccan to a fun-filled day at Disneyland.
"Somebody stop the time from flying by ..." the star wrote. "My Queen Monroe Cannon turned 6 today! And this dude is a Force to be reckoned with! A real rock star! Mr. Moroccan Scott Cannon Happy 6th Birthday!"
Carey herself shared a throwback photo with Monroe and Moroccan, and poked fun at herself in the caption. Cannon confirmed last week that Carey gave birth to their twins with her song "Fantasy" playing in the background.
"I can't believe it's been six years since you two came into this world to the live version of Fantasy.. 'the applause!!!' I love you both more each day. You are the light of my life #Supernatural #HappyBirthday #RocnRoe," the singer wrote.
Cannon, who split from Carey in 2014 after six years of marriage, shared the "Fantasy" story Friday on The Wendy Williams Show while naming the most "diva" thing Carey has done. He previously told The Gayle King Show it was a live version of the song.
"My wife wanted to make sure that when the babies came out, that they came out not only to a Mariah Carey song, but a live performance from Mariah Carey ... so they came out to a round of applause," the actor said in 2011.