Research by the Pew Research Centre in Washington found that just 51 per cent of young people in the US aged between 13 and 17 years old use Facebook.
This is a dramatic plunge from the Pew's previous study in 2015 when 71 per cent of teens surveyed said they still used the social media platform.
Young people said they favoured YouTube, Instagram and Snapchat over Facebook.
YouTube, owned by Google, proved the most popular social media platform among teenagers, with 85 per cent of young people saying they used the video channel site.
Instagram - which is owned by Facebook's Mark Zuckerberg - was used by 72 per cent of the teens surveyed and Snapchat - still owned by founder Bobby Murphy - was used by 69 per cent of those questioned.
A study by eMarketer study published in February estimated that Facebook's user base among Americans aged 12-17 had declined by 9.9 per cent in 2017. This was nearly triple the amount than eMarketer had predicted in 2017.
The news of Facebook's fall in popularity comes as the social media giant announced it is closing down its "Trending" tab.
In the wake of various fake news scandals all over the world, Facebook is axing its trending news service.
Alex Hardiman, the company's head of news products, said in a blog post: "We're exploring new ways to help people stay informed about timely, breaking news that matters to them, while making sure the news they see on Facebook is from trustworthy and quality sources."
The tool launched in 2014 in a bid to compete with rival Twitter.
Facebook is considering a 'breaking news' label that publishers can add to their stories.