Wendy Hall, 33, abandoned her little boy Malakye in a locked house with no gas or electricity so she could go and visit her partner.
But the youngster unlocked the door and wandered onto a busy city centre road, where he was struck and killed by a taxi.
A court heard that ‘popular’ schoolboy Malakye had been left alone in a dark, locked property in Lindley Road, Bradford, West Yorkshire, on the night of August 11, last year, with only his mum’s mobile phone to play with.
But at around 10pm Malakye was run over and fatally injured on Manchester Road – the main route out of the city.
Bradford Crown Court heard that Hall had left her mobile phone with Malakye for him to play on while she was away, but it appeared that he got out of the house shortly after she left.
When a police officer came across the scene of the fatal collision, the damaged phone was found in the boy’s possession and inquiries led them to the house which was in darkness with the door open.
Hall was subsequently traced to her partner’s home and she was taken to the Bradford Royal Infirmary to identify her son’s body.
Prosecutor Abigail Langford said when Hall was interviewed the next day she admitted leaving Malakye at home on his own.
Miss Langford said: “She told officers she had left the door to the premises locked so that Malakye could not go out.”
The court heard that Hall had moved from the Lindley Road address to live with her sister but had gone back there to pick up some belongings, intending to take her son to her partner’s but the boy changed his mind about going.
Miss Langford added: “She said she did not think Malakye could use the bolt on the back door.”
“The Crown say this was a deliberate disregard for the welfare of Malakye. A deliberate decision to leave him in a house which had no electricity or gas.”
Hall pleaded guilty to the neglect charge and was jailed for three years.
She also received an additional 18 months in prison for other matters.
Solicitor advocate Saf Salam, for Hall, said she had left Lindley Road two or three weeks before the death of her son.
Mr Salam said Hall, who had no previous convictions, had been diagnosed with bipolar disorder and had suffered from depression and anxiety since her teens.
He submitted that Hall’s culpability could be reduced due to her mental disorder.
“The police found your mobile phone in Malakye’s clothing and you were to say you had given it to him so he could play on it while he was alone in that house which had no electricity or no gas,” Recorder Tahir Khan QC told Hall.
“I’ve no reason to doubt you locked the door to stop him getting out but as we know he did with those tragic consequences.
“This is category one harm in my judgment. The deliberate act of leaving Malakye alone and vulnerable resulted in his death.”
Following his death, Malakye was described as a “happy and funny” child with a “bright smile.”