THE mother of the three-year-old WA boy who was inside a car which was allegedly stolen from East Victoria Park has thanked those involved in the search adding her little boy is safe at home and 'already pestering his sister'.

Glenda told reporters at a police press conference outside her home that she was extremely grateful to police and the wider public for their help in trying to locate her son Joe.

"First of all I would like to thank the Kensington Police as well as the multiple officers who searched for Joe this afternoon," she said. "I would also like to thank the media for making this breaking news and helping to spread the message.

"I would like to thank the general public, friends and family who have walked, biked and driven to search for Joe in the area.

"The outcome was exactly what we had hoped for and we are tremendously pleased.

Camera Icon Little Joe Credit: PerthNow

"Joe is safe and well, already pestering his sister and most importantly reunited with his Christmas train. As you can understand this has been an extremely difficult afternoon for our family and we respectfully ask for some space this afternoon."

Little Joe and the stolen Subaru Impreza were found by a member of the public who had received an Emergency Alert via text message just before before 4pm on Gloucester Street in East Victoria Park. The message, which is only used in life-threatening situations, was sent to more than 250,000 landlines and mobile phones in the area.

Superintendent Brad Sorrell from the South East Metropolitan District said police mounted the massive search for the vehicle after they received a report at around 1.50pm that a dark blue Suburu Impreza hatch had been stolen from the driveway of a house in East Victoria Park with little Joe inside on Friday afternoon.

He said Joe's parents had just returned home, parked the car in the driveway, opened the house and momentarily left him sleeping in the car with the air-conditioning on as they entered the house with their daughter.

He said the offender or offenders took the car and drove through the the white picket fences outside the home.

And while no one has been arrested in relation to the incident, Superintendent Sorrell gave this warning to those responsible: "The person who did this, we are coming for you."