Kelenna Azubuike and Anthony Randolph both added 18 points and Andris Biedrins had 12 rebounds as the Warriors grabbed an early lead and never relinquished it.
Andrew Bynum lead Los Angeles with 19 points and six rebounds while Kobe Bryant had 15 points on 5-for-11 shooting as the Lakers lost at the site of some of the franchise's greatest victories.
The Forum served as the Lakers' home court from Dec. 31, 1967 to May 23, 1999. With its bright yellow-and-orange seating pattern and yellow-spoked roof, the circular arena provided an up-tempo backdrop for six NBA championships and an electrified stage for the Magic Johnson's "Showtime" era of the 1980s.
The Lakers, who now play at Staples Center in downtown Los Angeles, generally schedules two preseason games in Hawaii during training camp.
After opting not to travel to Hawaii this year, the defending NBA champions needed to find new locations for preseason games. When the NBA rejected an initial request for an outdoor game at the Los Angeles Coliseum, the Lakers quickly arranged for a return to the Forum, which is now owned by a local church.
"Thanks for allowing us to come home for one night," exclaimed guard Derek Fisher to the crowd in a brief pregame ceremony. Fisher and Bryant are the only current Lakers who played for them during the Forum days.
Although Fisher arrived to find his gear sitting in the same locker he left behind 10 years ago, there was some updating required to play the first NBA game in the Forum in a decade.
The Lakers had to transport the floor and baskets from Staples Center to the Forum. Videoboards had to be added in the rafters behind each basket because the center court scoreboard has long been removed.
Once they got around to playing, Golden State quickly tried to spoil the homecoming.
Ellis opened with 7-for-10 shooting and 16 points to lead the Warriors to a 52-48 halftime lead. Azubuike then scored seven straight points as Golden State built a 69-55 lead midway through the third.
Jeffrey Osborne, who first performed the national anthem at the Forum in 1979, returned 30 years later to do the same Friday. The R&B artist also sang the anthem at Lakers home games during the 2008 and 2009 NBA Finals. ... The Lakers beat Golden State 118-101 in Anaheim on Tuesday. ... Warriors G Stephen Jackson picked up five fouls and a technical in less then nine minutes of the first quarter and did not play again.