YouTube's most popular star earned $7m (£4.5m) in 2014, according to Swedish newspaper Expressen.
Felix Kjellberg, 25, known to fans as PewDiePie, records himself playing video games and uploads his reactions online.
He has 37 million followers on the video-sharing website - more than One Direction and Taylor Swift.
"He appeals to an attractive demographic of teens and young adults," said Ian Maude, from Enders Analysis.
"It's strange to imagine that somebody can earn so much from YouTube, but the equivalent of half the UK is [following] his videos," he said.
On Tuesday, Mr Kjellberg posted a video titled Let's Talk About Money which has clocked up 1.6 million views in under 24 hours.
Addressing his fans, the Swedish gamer said: "Whenever it comes out how much I made a certain year, people just get so shocked. A lot of people are also very, very angry."
"They think I just sit on my ass all day and yell at the screen over here. Which is true. But there's so much more to it than that," he added.
Profits from YouTube
Expressen looked at dividends paid by Mr Kjellberg's companies in order to work out how much he had earned.
In July 2014, Mr Kjellberg confirmed to an audience on Reddit that he had earned "roughly" $4m in 2013.
Responding to critics, he posted: "I still spent far more money on charities than anything I've ever spent for myself."
YouTube continues to be a profitable enterprise for its top tier stars, who earn money from advertisements placed around their videos.
The site's terms and conditions forbid creators from disclosing how much they earn, but on Monday gamer Olajide Olatunji, known as KSI, told the newspaper Metro he had earned enough money to buy his parents a house.
Although some stars supplement their income with product placement deals, Mr Kjellberg says he does not do very many.
"I make more than I need from YouTube," he wrote on Reddit. "With that freedom, but also to respect my fans for making that possible, I don't end up doing many endorsements."
'It doesn't happen for everyone'
Mr Maude, of Enders Analysis, has a word of caution for anybody eyeing up YouTube with dreams of becoming a millionaire.
"As with many things, a few people at the top do exceptionally well but there's a long tail of people who don't make any money at all," he said.
"People have to see something special in you. It doesn't happen for everyone."
In his video posted on Tuesday, Mr Kjellberg said: "It seems like the whole world cares more about how much money I make than I do myself."
He thanked fans for their support and added: "I'm just happy doing this. I would be doing it even if I was not as big as I am."