The robbery happened at 7:12 a.m. Monday at 4201 North Broad Street.
Police say an employee saw the man put several dental care items in a blue shopping bag and a remote-controlled helicopter inside the baby stroller.
When the man tried to leave the store without paying, police say he was stopped by store employees.
The man then struggled with the workers, police said. That struggle continued outside the store where the man allegedly pulled a knife.
The suspect then fled on foot.
He is described as a black male, about 40 years old, standing about six feet tall, weighing 180 pounds wearing a black hooded sweatshirt, gray knit cap and dark pants.
Anyone with information is asked to contact Philadelphia Police at 215-686-TIPS (8477), text a tip to PPD TIP (773847) or through PhillyPolice.com.