An 18-year-old man has been charged over the theft of a busker's takings in Sydney's Pitt Street Mall.

Chilean guitarist Martin Campos, 38, happened to be livestreaming his performance on Facebook when the incident happened.

In the footage, Mr Campos can be seen leaping off his chair and running after a thief who swiped his earnings from an open guitar case at about 5:45pm on Saturday.

Martin Campos was targeted while busking on Pitt Street Mall. ( ABC News: Jean Kennedy )

Members of the public also intervened and a teenager from Hillsdale was captured and restrained until police arrived.

Mr Campos said he had been busking since arriving in Australia three years ago and was using the income to fund his English language studies.

He said he had damaged his $3,000 guitar while chasing after the alleged thief.

"I threw my guitar at his legs and he fell to the floor and I caught [the alleged thief]," he told ABC News.

He said he felt sorry for the alleged thief but buskers worked very hard for their income, often performing more than 10 hours a day.

"Fortunately we love what we do, but the problem is when you put all your life into something, to bring your music to the people, and some guy grabs your money — it's really, really annoying," he said.

The teenager was arrested and taken to Day Street Police Station where he was charged with larceny and goods in personal custody suspected being stolen.

He was granted bail on Sunday.

Pitt Street Mall is a popular location for buskers because it is a busy retail hub.