The 18-year-old man who kicked a security guard in the head at a youth festival has been sent to jail after breaching his bail conditions and leaving the country for a wedding weeks before he was due to be sentenced.

Martin Fulton in June pleaded guilty in Perth Magistrates Court to assault occasioning bodily harm and trespassing after he jumped the fence at the Good Life Festival on February 27 and kicked security guard Michael Rigby in the head as he was trying to restrain another man.

The incident was caught on video and went viral shortly after the festival.

Fulton was due to be sentenced on Tuesday but his lawyer revealed in court that the teenager had not completed his pre-sentencing assessment because he had left the country to attend a wedding with his family.