The young person was arrested within minutes of the alleged armed robbery on Thursday afternoon.
Police were called to the Davidson St service station about 4.40pm.
Murray River Police District Chief Inspector Jy Brown said based on a description from the staff member, a young person was arrested nearby about five minutes later.
Police allege the young person entered the store carrying a knife, threatening the employee while demanding cash.
The staff member co-operated.
Once the undisclosed amount of money had been handed over, the young person is reported to have thrown the knife away and left the store.
After being spoken to by detectives, the young person was charged with assault with intent to rob.
“Forensic examiners from Albury attended and seized a number of items of interest from the store,” Chief Insp Brown said.
“Thankfully the employee sustained no physical injuries, and police are continuing their investigations with the help of a number of witnesses.
“The young person appeared in Deniliquin Children’s Court on Friday, and was granted strict conditional bail pending another court appearance.”