The survey of 18 areas in Lebanon identified more than 1,500 children living and working on the street, although its authors said the real number nationwide could be three times higher.
The study comes as Syrian refugees in Lebanon struggle to make ends meet, nearly four years into the bloody conflict in their home country.
Lebanon has also been stretched by the influx of Syrians, who are competing with its four million citizens for limited resources.
Of the 1,510 children identified by the study, 73 percent were from Syria, including Palestinians who had been living in the war-torn country, the study found.
It is the first comprehensive study of children working in the street in Lebanon, though it did not cover child labour more broadly, which has also increased with the influx of Syrian refugees, more than half of whom are children.
The research, commissioned by Save the Children, UNICEF, the International Labour Organisation and the Lebanese labour ministry, found 42 percent of street children were illiterate.
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A majority had never been to school and although 40 percent expressed a desire to learn, just three percent were attending classes and working on the streets.
Nearly 45 percent of the children were involved in begging, with another 37 percent sell items such as chewing gum, flowers and tissues.
Working an average of more than eight hours daily, the children reported earning just over $11 a day.
Most of those surveyed, 54 percent, were between 10 and 14 years old, but more than 25 percent were under the age of nine.
The report was released with videos featuring the testimony of street children voiced over animated drawings of their experiences.
"A lot of people mocked me, insulted me and beat me," recalled 11-year-old Mustafa in one of the videos, describing his life selling flowers to raise money for his family back home.
"Once a drunk man came out of a pub and stabbed me in the arm with a knife," he said.
"My favourite day was when I would go to the money transfer office to send money to my family in Syria."