With closest challengers Manchester City in FA Cup action, Mikel Arteta's side took full advantage, bouncing back from their Europa League exit at the hands of Sporting Lisbon to beat their London rivals 4-1.
Saka scored twice and set up the opener for Gabriel Martinelli, becoming the first Premier League player this season to reach double figures for both goals and assists.
Four years on since he swore at his own fans when his substitution in this fixture was cheered, Granit Xhaka's fine season continued when he turned home the third after the interval.
Palace, who sacked former Arsenal captain Patrick Vieira on Friday, at least got themselves on the scoresheet as Jeffrey Schlupp's second-half consolation under caretaker boss Paddy McCarthy ended a near seven-hour scoreless run.
Both Takehiro Tomiyasu and William Saliba missed out through injury for the hosts as Ben White and Rob Holding came into defence.
Palace were inches away from taking the lead as a deflected Wilfried Zaha strike came back off a post, the ball catching goalkeeper Aaron Ramsdale on the back before squirming wide.
Martin Odegaard had Arsenal's first attempt on goal, the skipper's effort palmed away by Joseph Whitworth, the 19-year-old making just his second senior appearance for the Eagles.
After a slow start, the league leaders would break the deadlock through Martinelli - the man whose saved penalty cost Arsenal in their shootout loss to Sporting.
Zaha was caught ball-watching as White nipped in ahead of him, playing in Saka, whose cross was controlled and finished well by Martinelli.
The hosts were now well on top, the combination of White, Saka and Odegaard causing Palace all sorts of problems on the right.
Thomas Partey headed a free-kick wide and Odegaard screwed another strike past a post as Arsenal pushed for a second before the break.
The goal would come courtesy of Saka, who collected a smart pass from White before finishing low past Whitworth as a VAR check confirmed the England winger was onside.
Saka then saw an effort cleared off the line as Arsenal started the second half in the same dominant manner as they ended the first.
Any Palace threat seemed to come through Zaha and he stung the palms of Ramsdale as the visitors looked to half the arrears.
Instead, they would fall further behind as Xhaka exchanged passes with Leandro Trossard before finishing from close range, although Schlupp would pull one back as he finished from a corner.
Zaha dribbled a shot across Ramdale's goal and wide as they went in search of an unlikely second but once again they were immediately caught out at the other end.
Kieran Tierney, who replaced Oleksandr Zinchenko after Schlupp's goal, had far too much space on the left and crossed for Saka to turn home a brilliant first-time finish.
Arteta shuffled his pack in the closing stages to give much-needed minutes to his squad players as they saw out the final minutes to open up a healthy lead heading into the international break.