Thomas Boffey dialled 999 and climbed over the child gate let in the police after his mum Kayleigh Boffey, 33, fell down the stairs.
Kayleigh fell unconscious when she smacked her head on the stairs, but her toddler son didn't panic.
Instead he called 999 just like he had seen on animated YouTube series Robocar POLI - about a cartoon police car, ambulance and a fire engine.
The little tot managed to tell police "mummy's fell upstairs", before mounting an escape over the stairgate with a chair, and rummaging through the pushchair for house keys.
Not only did he find the correct key, he opened the front door and led paramedics and police officers to his mum.
Mum-of-two Kayleigh was treated in hospital for knee, ankle, shoulder and hip injuries, but is now home recovering with mini hero Thomas.
Mum-of-two Kayleigh from Rowley Regis, West Mids, said: "I knocked myself out and he managed to ring for help - it was amazing really,
"Words cant describe it. I'm extremely proud of him.
"He's like a mini superhero and, especially for his age, it's really amazing how he knew what to do and he understood and didn’t get scared.
"I want people to know what my son did and how important it is to learn kids what to do if anything happens in an emergency."
Kayleigh and her Thomas were alone in their house when, at about 2pm, the boy had a toilet accident.
As the single mum went up the stairs to get him some clean clothes, she was overcome by stomach pain from her hernia and enlarged spleen.
She said: "I remember shutting the stair gate, and the next minute I knew I woke up speaking to someone on the phone, and then the police were in the house."
Little Thomas saw that his mother wasn't responding but, thanks to some educational YouTube videos, he knew exactly what to do.
Kayleigh had seen the 'Robocar POLI' videos advertised on the streaming site while watching something else, so put them on for her son.
The originally-Korean series tells the story of a cartoon police car, ambulance and a fire engine, and teaches children how to respond to an emergency.
Kayleigh said: "He climbed up onto my window sill in the living room to get my phone and he managed to phoned the operator.
"They couldn’t understand what he was on about but directed him to the police."
The mum was drifting in and out of consciousness, but can remember seeing her son trying to push the phone to her through the child gate.
She said: "My son managed to push a really heavy chair to the gate, manged to climb over, get the keys from off the push chair, put the right key in the door, turn it and open the door.
"I think he knew how to do it by copying me, I always tell him 'this is the key to open the door'.
"The police said ‘can you open the door little man?’ and he managed to do it.
"The police came in and he said 'Mummy won't wake up'."
Kayleigh, who is currently unemployed, says there were at least seven medics and four police officers from from West Midlands Police that came into her home to help.
She said: "It was quite shocking and scary for me but the way they made Thomas feel was really nice.
"They took him straight out without upsetting him and saying 'Mummy's absolutely fine'.
"They didn’t make him scared and kept saying 'you're a real hero'."
Officers drove Thomas to stay with his great-grandmother Rita Waldron, 72, in the police car, and let him push the buttons and turn on the lights on the way.
Kayleigh was taken to Russells Hall Hospital to be X-rayed, and it was found she'd damaged her knee, ankle, shoulder and hip during the fall.
She is home recovering now with Thomas and daughter Ruby-May Boffey, nine, who was with Rita at the time of the fall.
Kayleigh wants to share the story to urge other parents to teach their children what to do in an emergency.
She said: "It's important to show them stuff like that so they can understand what numbers and call for help.
"If mum or dad in the family get hurt and they're on their own they know how to stay safe and get help somehow.
"He was so young but he understood what to do.
"He managed to tell the police where he lived and open my door to let the ambulance and police in to treat me.
"Even the police said he's a very special little boy."
Head of Force Contact Andy Beard said call handler Morgane did well to keep the boy calm, build a rapport and glean important information about what had happened.
He said: “The boy was clearly confused and worried…but he’d done brilliantly at such a young age to know that if you dial 999 we are here to help.
“Morgane built up a rapport with the boy, remained calm and offered him reassurance right up till the point officers and the ambulance arrived to take over.
“Our call handlers are highly trained to deal with emergency situations like this, including how to advise people to stay safe and perform first aid.
“Just like officers out on the streets, they can be lifesavers.”