Most people dream of running away with the circus but Livvie wanted a taste of the real world.

The monkey from the Lennon Bros Circus was on the back of a pony when she decided to make a run for it on Sunday morning in Sydney's south.

Luckily, the lion enclosure at Lennon Brothers Circus was not left open as well.

St George Police Inspector Rob Stark said a trainer had left a gate at the circus ajar and Livvie "tasted freedom".

"Livvie obviously got excited, saw the door was ajar, jumped off the pony's back and off she went," he told AAP.