The pop star, who became a global sensation when the song was released on Oct. 23, 1998, tweeted a sweet tribute to her fans on the anniversary.
"It's hard to put into words what today means to me... 20 years ago, the world heard my music for the very first time!" she said.
It’s hard to put into words what today means to me… 20 years ago, the world heard my music for the very first time! So much has happened since then… but what I really want to say is thank you to my amazing fans who have been there for me since day 1... pic.twitter.com/oeMipXCSl9
— Britney Spears (@britneyspears) October 23, 2018
The former Mousketeer included a 32-second clip showing some behind the scenes footage of her school-girl themed music video that was filmed at Venice High School in Los Angeles.
"So much has happened since then... but what I really want to say is thank you to my amazing fans who have been there for me since day 1," she said.
"...Baby One More Time" reached No. 1 in dozens of countries around the world that year.