The 10-test All Black, who shared in his country's World Cup success on home soil in 2011, was released by Super Rugby's New South Wales Waratahs last year for "wellbeing reasons" but returned home to play for amateur provincial side Wairarapa Bush before he moved to Waikato.
The 28-year-old will return to the top-level of provincial competition in New Zealand for the first time since 2015 when he played for Hawke's Bay.
"That's the first step in the right direction for me, and I've just got to prove through my performances - and off the field - that I'm in a good space," he told local media on Tuesday.
"I've been surrounding myself with good people. I'm living with a good family and I obviously had to make changes in my personal life that were made some time last year.
"I'm just got to keep doing good things that will help me with rugby."
Once a player with the world at his feet, Guildford was hit hard by the death of his father in 2009 and jettisoned by New Zealand Rugby after a number of alcohol-fuelled incidents.
The governing body said in January it was still some distance from welcoming Guildford back.
"He needs to demonstrate to himself and to others that he has let down that over a sustained period of time he is a changed person, before we would entertain employing him again," NZR general manager Neil Sorensen said.
(Reporting by Ian Ransom in Melbourne; Editing by Greg Stutchbury)
