The High Court in Livingston heard Hayley died of a brain injury after her mum Catherine left the tot in the care of her boyfriend McKay, a former soldier.
Hayley Davidson.
Police were called to West High Street in Buckhaven on February 14 2016 and Hayley was taken to hospital where she died three days later.
An investigation was launched by Police Scotland’s major investigation team.
Reacting to the verdict, senior investigating officer Detective Chief Inspector Scott Cunningham said: “I want to extend my sincere condolences to Hayley Davidson’s family.
“Gordon McKay’s despicable actions resulted in the death of an innocent baby and had devastating consequences for her family.
“I would also like to pay tribute to my team who carried out a thoroughly professional and robust investigation in very distressing, emotive and difficult circumstances.”
McKay was granted bail ahead of his sentencing last month.
