Nick Finigan, who fled the island two years ago shortly before his first scheduled trial date, was found guilty of a total of eight historic abuse counts against a boy and a girl.
After a long nine-day trial, Jurats took just two hours to make their unanimous decision.
Finigan, who denied all of the offences, has been remanded in custody and will be sentenced in November.
The court heard how the two children, who were both under six at the time, had visited Finigan on a number of occasions at a house in St Peter Port shortly after 2000.
It was there that he took the girl to the toilet and committed acts of gross indecency or indecently assaulted her.
He would take the boy to a bedroom, the toilet or the lounge to indecently assault him or commit acts of gross indecency.
