William Billingham was jailed in 2018 with a minimum term of 27 years after being found guilty of murdering Mylee Billingham.
The Prison Service said 57-year-old Billingham died last Friday, but did not confirm the cause of death.
A trial at Birmingham Crown Court was told primary school pupil Mylee was stabbed in January 2018 in a “revenge” attack motivated by jealousy and anger against Billingham’s ex-partner, Tracey Taundry.
Jurors were told Billingham, of Valley View, Brownhills, near Walsall, killed Mylee after dragging her into his bungalow when her mother came to collect her.
He was also given a two-year concurrent jail term for holding a kitchen knife to the throat of Miss Taundry moments before the murder.
The father-of-six – the brother of TV’s SAS Who Dares Wins star Mark Billingham – attempted to kill himself while on remand during the trial.
After the hearing, the then 55-year-old was said by his lawyer to have no desire to live due to his remorse over the killing.
Offering mitigation before sentence was passed in October 2018, defence barrister Balraj Bhatia said: “This court will punish him in terms of years. His punishment – to use his own words – is that he is still breathing.
“Just this morning, as I was preparing him for the impact statement, there was a palpable rush of hatred from every prisoner that walked by the cell.
“To use his own words, he cannot live with this, nor does he desire to live with this.”
A Prison Service spokesperson said: “HMP Birmingham prisoner William Billingham died in custody on 19 March 2021. The Prisons and Probation Ombudsman has been informed.”