The man will face court today charged over the incident that took place about 10.30pm on Friday.
He allegedly approached the 14-year-old girl and her friends on the dancefloor at the Moore Park concert of US rapper Juice Wrld.
Police will allege the unknown man sexually touched the girl as he attempted to lead her toward the stage and away from the group.
The girl reported the incident to her mother, who was also in attendance, and police were notified.
Following investigations by detectives from Surry Hills Police Area Command, a 26-year-old man was arrested at Windsor Police Station about 10.30am yesterday.
The North Richmond man was charged with two counts of intentionally sexually touch child aged 10-16 years.
He has been refused bail to appear at Penrith Local Court later today.