He was arrested at 4am on July 4 after a member of the public saw him tagging the gallery, and phoned police.
Edwards faced three charges of intentional damage and one of possession of graffiti utensils for the gallery graffiti. He was convicted and discharged on two damage charges and the possession charge. He was convicted and ordered to do 40 hours' community work and pay $60 to Auckland Council on the third damage charge.
Auckland psychotherapist Kyle MacDonald said tagging could not technically be diagnosed as an addiction.
"Tagging is clearly significant for some people and a compulsive behaviour that the person is getting a kick out of and is having difficulty stopping requires treatment to resolve," he said.
Auckland Council community facilities manager Kevin Marriot said the council would spend $4.7m cleaning up graffiti this financial year.
Auckland Police spokeswoman Noreen Hegarty praised the member of the public for calling police.