Homeless Deyan Deyanov, 29, was convicted by a jury of nine at the Provincial Court in Santa Cruz de Tenerife.
He repeatedly stabbed and beheaded Jennifer Mills-Westley, 60, who had been shopping in the popular resort of Los Cristianos on 13th May, 2011.
Deyanov had denied murder. His defence had argued he was not criminally responsible for his actions because he suffers acute paranoid schizophrenia.
He faces a sentence of 15 to 20 years in a psychiatric unit.
More top news
West Ham's dramatic FA Cup win over Liverpool will go down as one of the club's greatest ever games, says Slaven Bilic.
Scotland will see a mixture of sunshine and showers today, with some showers turning wintry in places.
Two men seen as alternative voices to the US political establishment have won decisive victories in the New Hampshire presidential primary.