Ryan Kaji, from Texas, topped the Forbes rich list of the highest paid YouTube stars, earning an estimated $26m (£19.8m).
The American business magazine looked at how much money the so-called influencers made from the video sharing platform in the year to June 2019.
Ryan Kaji, who has almost 22 million subscribers, came first in the list for the second year in a row, with his earnings reportedly rising from $22m (£16.8m) in the last 12 months.
He started out on the channel when he was just three-years-old by reviewing toys and now does science experiments for his legion of fans.
Forbes says the youngster has also branched out beyond YouTube with a line of more than 100 toys and clothing items – and he also has a show on Nickelodeon and a deal with US television network Hulu.
Also making the coveted top 10 is Dude Perfect – a group of five friends in their 30s who play sports, perform stunts and break Guinness world records. They came second in the list, earning $20m (£15.2m).
Russian-born five-year-old Nastya, real name Anastasia Radzinskaya, was third with $18m (£13.7m), thanks to videos in seven languages that show her playing with her father.
Other YouTubers who also made the list include PewDiePie, real name Felix Arvid Ulf Kjellberg, who recently announced he is taking a break from the platform because he is “tired”. He was joint seventh in the list after apparently making $13m (£9.9m).
British YouTuber Dan Middleton dropped from number four in the list last year to ninth in 2019 – with his earnings falling $6.5m year-on-year – to $12m (£9.1m).
Collectively, the top 10 earned a total of $162m (£123.8m).
Forbes top 10
1 Ryan Kaji $26m
2 Dude Perfect $20m
3 Nastya $18m
4 Rhett and Link $17.5m
5 Jeffree Star $17m
6 Preston Arsement $14m
7 PewDiePie $13m
7 Markiplier $13m
9 Daniel Middleton $12m
10 Evan Fong $11.5m