Leila Borrington, aged 23, claimed the boy had fallen from a chair and banged his head after paramedics found him unresponsive on 7 August last year.
Three-year-old Harvey Borrington later died in the hospital as a result of serious head injuries.
Medical experts concluded that his injuries were caused by repeated blows, rather than by a one-off fall.
Several other older injuries were also found on his body, including a broken arm.
Borrington, who is not Harvey’s mother, had been caring for the child at her home in Jacksdale at the time of his collapse.
Rather than phone an ambulance, she filmed a video of Harvey lying on the floor and sent it to his father who was out of the house at the time.
During a lengthy trial at Nottingham Crown Court she denied she had ever hit Harvey, but was today (Tuesday 28 February) convicted by a jury of his manslaughter.
Borrington was also convicted of causing grievous bodily harm and assault.
She was, however cleared of an alternative charge of murder and two additional assault charges.
She will be sentenced on 16 March.
Detective Inspector Simon Harrison, of Nottinghamshire Police, said: “This was a tragic incident that shocked the local community.
Harvey was a much-loved little boy who was cherished by his parents and his wider family.
“As a police officer I am pleased with the decision of the jury in this case, but I acutely aware that it is of no consolation to those left behind.
“This has been a very lengthy and difficult investigation and I would like to thank everyone involved in getting us to this point.”
