Mikel Arteta's team ended their three-game winless run in style at a tough venue on the road and only strengthened their title charge.
Martin Zubimendi, Viktor Gyokeres and Gabriel Jesus were all on target, while Leeds goalkeeper Karl Darlow added an own goal.
Manchester City and Aston Villa can trim Arsenal's lead back to four points on Sunday, but the Gunners demonstrated why they will take some catching.
Having beaten Leeds 5-0 in August, Arsenal enjoyed another romp against Daniel Farke's team.
Six points and nine goals against the promoted Yorkshire side could go a long way to helping Arsenal's title bid, which had been wobbling in recent weeks.
Against an in-form Leeds who'd lost just one of their last 11 in all competitions, the trip to Elland Road was a potential banana skin for the league leaders, especially when their England forward Bukayo Saka was injured in the warm-up and had to be withdrawn shortly before kick-off.
But in his absence, Arsenal, who gave Declan Rice his 300th Premier League appearance, totally dominated, with Zubimendi heading the visitors in front after 27 minutes and Darlow punching Noni Madueke's corner into his own net before halftime.
Gyokeres scored for the fourth time in six games in the second half and substitute Gabriel Jesus spun to fire low into the bottom corner late on.
Elsewhere, Chelsea came back from two goals down at home to beat West Ham 3-2 and climb up to fourth, with Enzo Fernandez hitting the winner in the second minute of added time.
Chelsea had trailed 2-0 to goals from Jarrod Bowen and Crysencio Summerville at halftime, with Blues' coach Liam Rosenior's decision to make seven changes looking like a costly one.
But three halftime substitutions paid off, with Joao Pedro and Marc Cucurella coming off the bench to score and level the game by the 70th. Then they took all three points when Fernandez swept in the winner from inside the box.
The dramatic finish sparked a mass confrontation between the players and Jean-Clair Todibo was sent off for violent conduct.
Last-placed Wolverhampton lost for the 18th time this season, 2-0 at home to Bournemouth.
Goals from Junior Kroupi and Alex Scott secured the visitors' victory at Molineux, which meant back-to-back defeats for Wolves after a recent mini-resurgence.
Everton scored in the seventh minute of added time to draw at Brighton 1-1 -- the second time this week they'd fought back to salvage a point.
After Monday's 1-1 draw with Leeds, the Merseyside club left it late to equalise at Brighton, who were leading through Pascal Gross.
Beto came on as a substitute only in the 89th minute and he was the one to deliver the crucial goal deep into added time.
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