Emergency services were called to a pharmacy on Anzac Parade, Kensington, at about 11am.
A man armed with a knife entered the store before threatening employees and customers.
He stole $200 in cash then fled the scene.
Michelle Spiro, an employee at the pharmacy, said staff there are “very shaken”.
“He put the knife towards her (the cashier) and said give me all your money. He came very close,” she said.
“We’re very shaken, it’s a horrible experience.”
The man was last seen heading north on Anzac Parade.
No one was physically injured during the incident.
It’s the second time the pharmacy has been robbed in the past three years.
Owners are now worried about the safety of their staff.
“When we used to see smiles and then someone come in with a covered face you would immediately know you were being held up,” Rosa Colagrossi, the owner of the pharmarcy, said.
Police conducted a search of the surrounding streets for evidence today.
Investigations are continuing, and anyone with information about the incident is urged to contact police.