The playtime adventures of Emily Cozmiuc, a three-year-old from Wembley, have racked up more than a billion hits and almost 1.5mn subscribers.
Popular videos include her trundling a tiny shopping trolley around Toys R Us, crawling through a giant caterpillar and being pulled along by her sister in a cart train full of Minnie Mouse toys.
Her family initially posted videos to keep relatives in Romania up to date with the progress of their children.
But the clips took off, and Internet ranking site Social Blade now estimates Emily could be earning between £36,000 and £585,000 a month from ad revenues.
Yesterday, her father Ciprian, 38, quit his job as a bank maintenance engineer in the City to concentrate on managing the channel He and his wife Larisa, 34, who shoots the videos, have lived in London for 12 years and have four daughters, aged three to 14.
He said: “Everybody loves Emily and we’ve been amazed how the audience grew from last year — it just exploded.
I was uploading videos for family to see what our kids are doing.
“Then we found out we could make money as well.
Emily enjoys what she’s doing, she likes to play with any toys.”
Emily’s sister Celeste, nine, often stars with her and has her own channel with more than 32mn views.
Cozmiuc said: “We were in a shop in Spain and a family were saying, ‘Look, look it’s Emily and Celeste’. With our family, they are very relaxed around cameras, but of course there are times she just doesn’t feel like filming.”
Much of the money earned from the channel is being put into savings to “keep her future secure”, he said.
Asked about criticisms of exposing such a young child to a worldwide audience, Mr Cozmiuc said: “You can have problems anywhere, but we make sure we take care of Emily.
“You can’t please everyone, you’ll always have someone who wants to argue with something, but most people say, ‘Well done’.”