Kim reached the milestone on Thursday and thanked her fans and followers, reports dailymail.co.uk.
"Can't believe I reached 100 million Instagram followers, all thanks to you! Get the stories behind my top pics," Kim wrote alongside a link to her website with a breakdown of her top five photographs.
Gomez, currently the most followed person on Instagram with more than 120 million devotees, was first to reach the milestone in September 2016. She was later joined by Grande, Swift and Knowles, and Portuguese football star Cristiano Ronaldo.
Instagram's own account, meanwhile, remains by far the most followed account overall, with 223 million.