Stephen Curry added 15 points and four assists for Golden State before leaving midway through the third quarter with a bruised left hip after a hard foul by Cleveland's Mo Williams.
Playing their first home game following an encouraging 2-3 road trip, the Warriors had little trouble against the NBA's worst team. Golden State made 14 3-pointers led by as much as 21 and had five players reach double figures.
Ellis led the Warriors in scoring but was equally effective dishing off, something coach Keith Smart has been pressing his veteran guard to do more of in recent weeks.
Ellis had 10 assists, the fourth time this season he's reached double digits in that category. That's encouraging news for the Warriors (15-21), who ended a four-game home losing streak to the Cavs.
It was a rough day all around for Cleveland (8-28).
Before the game the Cavs learned that reserve forward Leon Powe would be out at least six weeks after undergoing surgery to repair a torn meniscus in his right knee. Powe was injured in Wednesday's loss to Toronto but the full extent wasn't revealed until he had an MRI test early Friday.
The hard-luck Cavs were also without leading rebounder Anderson Varejao, who was still sore after spraining his left ankle late in practice Thursday.
"All you can do sometimes is shake your head when things like this keep cropping up," Cavs coach Byron Scott said before the game. "It's the opportunity for these young guys to show us what they can do."
Cleveland couldn't overcome its health issues and lost in Oakland for the first time since Nov. 4, 2007.
The Warriors got a scare of their own midway through the third quarter when Curry went down after the flagrant foul by Williams. Curry was slammed to the court on his stomach and lay prone for several anxious moments as Golden State head athletic trainer Tom Abdenour rushed to his side.
Curry was eventually helped to his feet but stayed in the game and made both free throws to make it 82-63 then went to the Warriors bench. He returned with just over 7 minutes left to play and Golden State up 97-83 but left less than two minutes later.
The Warriors led 65-49 at halftime and cruised home after that. The Cavs made one brief run, pulling within 91-81 early in the fourth quarter on a Sessions layup. Sessions then missed a chance to close the gap more when his layup attempt was blocked by Golden State's Vladimir Radmanovic.
Radmanovic finished with 13 points and Dorell Wright added 20 for the Warriors.
Cleveland lost despite getting a strong night off the bench from J.J. Hickson and Ramon Sessions. Hickson had 17 points and nine rebounds while Sessions added 13 points and five assists.
Manny Harris had season-highs of 16 points and 10 rebounds for the Cavs while Williams added 16 points and seven assists.
Notes: Warriors coach Keith Smart previously was a head coach in Cleveland during the 2002-03 season, albeit on an interim basis. Smart coached the Cavs to a 9-31 mark in 40 games after replacing John Lucas midway through the year. ... Hue Jackson, rumored to be the leading candidate to be the next head coach of the Oakland Raiders, sat courtside along with former Raider safety Eddie Anderson. The duo sat in seats owned by Mark Davis, son of Raiders owner Al Davis. ... Cavs Hall of Fame radio announcer Joe Tait underwent double bypass surgery and an aortic valve replacement in Cleveland. ... Golden State C Andris Biedrins had two points and eight rebounds in his second appearance after sitting out nine games with a sprained left ankle.