Michael Redpath, 62, was pulled from the burning property in Albion Street, Swindon, but died in hospital as a result of smoke inhalation and burn injuries, Winchester Crown Court heard.
Patricia Louise Hindle, 31, from Swindon, will be sentenced on Friday.
Supt Sean Memory said Mr Redpath's final moments "must have been terrifying".
Speaking after Hindle was convicted, he described how she "ran away from the scene and made attempts to cover up her crime by disposing of his keys and bank cards".
"Today the court found that she did kill him and that she intended to kill him."
Hindle, of Crombey Street, carried out the fatal attack in September 2014.
A woman has been found guilty of murdering a man by setting a house on fire and locking him inside.