This year, she has done more than 13 assignments, including a TV commercial for Sentosa and print advertisements for shopping mall VivoCity.
Last year, she did 26, encouraged by her mother, reports The Straits Times.
Ms Maia Lee, 31, owner of a children's costume boutique, says: "My daughter has the looks and talent, so why not use them?
While the money can be pretty attractive - a four-hour assignment involving photo and video shoots can pay from $300 to more than $1,000 - it is the fun of doing the assignments that draws some kids.
For Ms Lee, her daughter is also picking up soft skills on the set of commercial shoots.
"Other kids learn piano and ballet. My child learns how to interact and work with other kids and adults," says the former Singapore Idol contestant, who also has two sons, aged 12 and one.
The older boy, Tyrese, also acts and was in a corporate video for the Changi Airport Group earlier this year.
She is open to spending the money Julka earns, but it must help the girl's future.
Ms Lee says: "It shouldn't be for the latest fad or fashion accessory.
"I must be confident it will benefit her in the long run."