Graham Findlay, 26, of Orkney, was convicted of five charges involving youngsters he had befriended at Kirkwall Sheriff Court yesterday.
They included the serious sexual assault of a 16-year-old who he attacked after the boy turned to him for support following bullying.
Findlay also invited two boys, aged eight and 10, into a shed where he asked them to expose themselves before he did so himself.
Findlay's used social networking site and messaging services to carry out the abuses, including asking a child to take off his clothes before a webcam he was watching.
He was granted bail ahead of being sentenced next month and was placed on the sex offenders' register. He wept in court as the jury's verdicts were read out.