New Zealand Rugby Union confirmed the punishment following a misconduct hearing into the 22-year-old's behaviour in the Cook Islands, where he was reportedly attending a wedding, last month.
A statement on www.allblacks.com read: "The misconduct hearing followed reports of Guildford's alcohol-related behaviour which the NZRU has deemed were unprofessional and brought the game into disrepute.
"The NZRU has imposed a number of other sanctions on Guildford including a requirement to undergo alcohol treatment and counselling as directed at his own expense."
Guildford, a member of the New Zealand squad which won the World Cup on home soil in the autumn, will only miss one Super 15 match, with the ban also encompassing three pre-season games.
NZRU general manager professional rugby Neil Sorensen said: "Taking players out of rugby is not something we do lightly. But we have taken into account the fact that with regard to alcohol-related behaviour, Zac does not have an exemplary record.
"On this occasion, he embarrassed himself, his family, his team-mates, and New Zealand Rugby. We believe Zac brought the game into disrepute and the sanctions reflect the gravity of the situation and the need for a real pathway to recovery.
"To his credit, Zac himself has agreed that he needs assistance and recognises that both the NZRU and the Crusaders support him taking time to get himself right."
Guildford added: "I am embarrassed by what has happened, but I know that I let down the many people who support me. I am focused on getting myself into the place I need to be when I return to rugby next year."
The suspension means Guildford is not able to play in the Crusaders' first three pre-season fixtures in February and the opening match of the Super Rugby season against the Blues at Auckland's Eden Park on 24 February 2012.
He will be eligible for selection for the Crusaders week two fixture against the Highlanders in Dunedin on March 3.