The 23-year-old was on his way to deposit money at an ATM on Bridge Street just after 9.00pm on Wednesday when he was confronted by 3 men in Market Lane who punched him in the face, causing him to fall to the ground.
The trio took his wallet and mobile phone before running off.
The victim wasn't seriously injured and attended Muswellbrook Police Station to report the incident.
Anyone who may have witnessed the robbery is urged to contact Crime Stoppers on 1800 333 000.