Instagram has added 100 million new users in the past nine months to zoom past the micro-blogging site Twitter which currently has 316 million monthly active users.
Out of over 400 million users, more than 75 per cent of the Facebook-owned popular photo-sharing website's users now live outside of the US, Forbes reported.
"When Instagram was launched nearly five years ago, 400 million seemed like a distant dream," Facebook said in a blog post.
"Now, we continue to strive to improve Instagram in helping you experience the world through images and connect with others through shared passions," the post added.
Of Instagram's 100 million newest members, more than half live in Europe, Asia, Brazil, Japan and Indonesia.
More than 80 million photos are shared on the service every day, up from 70 million in June.
According to the global research firm eMarketer, Instagram's ad revenue will reach about $1.5 billion in 2016 and $2.8 billion in 2017.
According to estimates, Instagram's global ad revenue will be $600 million this year.
Instagram has recently improved its ad offerings after testing ads on its platform for the first time.