Michael Daymond was found guilty of the murder of Maya Chappell at Teesside Crown Court last month.
A jury unanimously agreed that the toddler had died from fatal head injuries inflicted by the 27-year-old.
Maya’s mother, Dana Carr was found guilty of allowing the death of the defenceless youngster as she knew what Daymond was doing but never raised the alarm.
Both defendants received prison sentences when they appeared back at court today for sentencing; Daymond will serve life with a minimum term of 20 years, and Carr was jailed for nine years for allowing the death of Maya.
The pair were each also sentenced to six years for child neglect – these sentences will run concurrently with their other offences.
Daymond was supposed to be caring for her while Carr was at work on the afternoon of September 28, 2022, when Maya fell seriously ill at her home in Shotton Colliery.
He called for an ambulance but not before ringing Carr and as paramedics and police carried out CPR, he took himself into another room to make a call to find out why his Universal Credit payments had been stopped.
Despite the best efforts of the emergency services, Maya was taken to the Royal Victoria Infirmary, in Newcastle, but sadly never regained consciousness and later died.
During the three-week trial at Teesside Crown Court, the jury heard how Daymond and Carr had only been dating for a matter of weeks when he moved into the house in Shotton Colliery where Maya lived.
Soon after, Daymond began looking after Maya while Carr was at work.
A significant number of bruises began to appear on Maya’s face and body, and the couple took her out of nursery so not to raise the alarm.
Family members raised concerns but were told that these were self-inflicted because Maya was nipping herself and walking into things.
Daymond, who did not give evidence at the trial, inflicted the injuries on Maya over several weeks when he was alone with her.
He would message Carr, 24, while she was at work with a series of lies to cover up his horrific behaviour.
Despite being alerted to the situation, Carr did nothing to stop her daughter getting hurt, instead frequently telling him she loved Daymond and would not leave him when he sought reassurance.
Maya sustained fatal head injuries at some point during a four-hour period when the only person to see her was Daymond.
Detective Superintendent Chris Barker, of Durham Constabulary, who led the investigation, said: “Maya was killed, we don’t why or what caused Daymond to carry out such an appalling crime – but he did.
“Sadly, nothing can change his unforgiveable actions but at least he, together with Carr, is now facing the consequences of Maya’s tragic death.
“Maya was a defenceless two-year-old girl who should have been able to trust Daymond – instead she lived in fear, and she couldn’t even rely on her own mother to help her.
“My heart goes out to those who truly cared about Maya. Today’s sentencing won’t bring her back but hopefully it will provide some closure and allow them to grieve.”