It happened around 1:30 a.m. on January 29 at the AMC 8 Theater in Deptford Township.
Police say the victim was threatened by a man armed with a knife.
"After realizing no money was available, the suspect fled the scene on foot through the rear emergency exit of the theater," police said in a news release.
The employee was not injured.
Anyone who has any information is asked to call Deptford police.