The main event was a Six-Pack Challenge–a non-elimination match consisting of six wrestlers for the vacant WWF Championship. Stone Cold Steve Austin served as the special outside enforcer for the match. The match included Triple H, The Rock, Mankind, Kane, Big Show and British Bulldog. Triple H pinned Rock after a Pedigree to win the WWF Championship.
The undercard featured X-Pac versus Chris Jericho, a Kennel from Hell match between champion Al Snow and challenger Big Boss Man for the WWF Hardcore Championship, New Age Outlaws (Mr. Ass and Road Dogg) versus Edge and Christian for the WWF Tag Team Championship, Ivory versus Luna Vachon in a Hardcore match for the WWF Women's Championship, The Acolytes (Faarooq and Bradshaw) versus Dudley Boyz (Bubba Ray and D-Von), Jeff Jarrett versus Chyna for the WWF Intercontinental Championship, Mark Henry versus D'Lo Brown for the WWF European Championship and Val Venis versus Steve Blackman.
The matches of the event featured special guest referees due to the WWF officials being out on "strike" due to continuous assaults on them by wrestlers. However, only one WWF official Jim Korderas served as the referee of the event. He refereed Dudley Boyz vs. The Acolytes, the WWF Tag Team Championship match and the WWF Championship match.
The previous Unforgiven event was held in April while the 1999 edition was moved to September as Backlash took Unforgiven's place. Unforgiven replaced Breakdown: In Your House that was held in September 1998. Unforgiven continued to being used as a pay-per-view for the month of September until its final edition in 2008 as it was replaced by Breaking Point in 2009.