Police said the employee was stabbed with a box cutter outside the store in the first block of West Jackson Boulevard at about 3:22 a.m.
About 10 minutes earlier, the suspect had attempted to steal items from the store, but was stopped by the employee. Police said the suspect later returned and threw a lottery machine at the employee, beginning the altercation that led to the employee being stabbed.
The worker was taken to Northwestern Memorial Hospital in good condition.
No one is in custody. Area Central detectives are investigating.