The network allegedly infiltrated 1.3 million computers and skimmed millions of dollars from victims' bank accounts.
He faces a maximum penalty of several prison terms of up to five years, but the Thames District Court judge said he would not jail the teenager, according to an online report from the New Zealand Herald newspaper.
Judge Arthur Tompkins set May 28 to hear the pre-sentence and reparation reports which would cover home detention, community detention, community work and a fine for Walker.
The newspaper said the FBI had implicated Walker as the ringleader of a group of international programmers who set up a "botnet" that infected a million computers with a virus.
A botnet is a network of hacked computers that can be controlled by a single computer via the internet.
Walker was arrested following an 18-month investigation by New Zealand police in collaboration with the FBI and Dutch authorities.
Police have released few details of the operation.
Eight people have been indicted, pleaded guilty or have been convicted since the investigation began last June, while another 13 warrants have been served in the US and overseas.