Xzibit -- I Do ... Plead Guilty to Wedding Day DUI

It's til death do they part for Xzibit and his wife, but it's only three years probation for the rap star ... after he pled guilty to driving under the influence ... the night of his wedding reception.

The November 2014 arrest really was something ... cops pulled over the rap star for speeding, but found he reeked of booze and blew a .14 ... nearly twice the legal limit.

X and his wife, Krista Joiner, had their wedding reception in Laguna Beach just before his arrest.

In addition to probation, X has to attend an alcohol ed program.