Detectives believe the woman was approached by the man who threatened her with a knife, forcing her into the driver’s seat of her silver Suzuki S Cross.
Police said the man sat in the back seat with her infant child, before forcing her to drive to electrical stores on the South Gippsland Highway, Cranbourne and Frankston Dandenong Road, Dandenong.
He demanded her to purchase Apple MacBooks at several stores, while he remained in the car with her baby.
Detectives said the man drove from the Dandenong store, while the victim was forced to remain in the back seat with her child.
He exited the car and fled the scene after arriving at Robert Booth Reserve in Dandenong, carrying four MacBooks just after 8pm.
The woman and her child were not physically injured during the incident.
Police said the man is perceived to be Asian in appearance and aged between 20 and 35 years of age.
He was wearing a grey coloured hoodie, with the hood over his head, a green fluro vest over the top of the hoodie and black/grey pants with black running shoes.
He was last seen carrying a shopping bag containing two Apple MacBook Pro computers in their boxes and two further boxed Apple MacBook computers under his left arm.