Canadian singer Justin Bieber. Picture: Bang Showbiz

Justin Bieber has reached 100 million followers on Twitter, becoming the second person to do so after Katy Perry.

The 23-year-old singer reached the social media milestone on Thursday and is only the second person to reach the huge number of supporters behind Katy Perry, who hit the target in June.

READ: Hackers share Justin Bieber pic on Selena Gomez's Instagram account

The microblogging website marked the occasion with a video featuring some of the 'Sorry' singer's most popular hashtags.

They wrote: "In each other's company since Tweet number one. Congratulations @justinbieber on #100MBeliebers (sic)"

The 'Never Say Never' singer then retweeted the post.

And Twitter also revealed the word 'Belieber' - the nickname for Justin's fans - has been retweeted 84 million times, and there have been over two billion mentions of 'Bieber or @JustinBieber' on the site.

The 'Believe' hitmaker's most popular tweet, from 2014, has been retweeted 638,000 times to date.

The popular post read: "YOU ARE ALL WORTHY NO MATTER WHAT ANYONE SAYS >> BE STRONG GOD IS WITH US ALL> MY BELIEBERS CHANGED MY LIFE> I WILL FOREVER BE GRATEFUL (sic)"

Justin has frequently deactivated his Instagram account over the years, but has stayed loyal to Twitter, using the platform to praise other artists, including Drake and Shawn Mendes, and in August 2015, he used the direct message feature to delight 49 of his biggest fans by sending them the lyrics to his song 'What Do You Mean' before it was released.

Fans of the Canadian pop star can get a special Justin emoji if they tweet the hashtag #100MBeilebers.

Katy, 32, has 103 million Twitter followers, while behind her and Justin are Taylor Swift with 85.5 million, Rihanna with 76.9 million, and Lady Gaga with 69.5 million.

Justin's ex-girlfriend Selena Gomez is currently the most followed person on Instagram with 126 million.