The performance doubled the Gunners' goal output for the season and ended Leicester's unbeaten opening run. Combined with the midweek win over Tottenham in the Capital One Cup, Saturday's victory represented a strong response to disappointing losses in the two preceding contests at Dinamo Zagreb and Chelsea.
Here are three things we learned from the match.
Don't get into a shootout with Arsenal
In truth, we could fill a report with accounts and analysis of the various ways Arsenal scored--incisive counterattack, deft crosses, individual skill off a set play, precise timing of a fullback run. That's testament to how rampant Arsenal's offense was in this match.
Allowed space by Leicester's high defensive line, Arsenal's Theo Walcott and Alexis Sanchez swooped into dangerous areas again and again. Leicester's midfield failed to put pressure on Santi Cazorla and Mesut Özil, giving those two pass masters many opportunities to pick out the runs of their teammates farther forward.
The numbers (from Opta via the StatsZone app) reveal the consequences.
Arsenal had 26 shots, an amazing 22 inside the Leicester penalty area, and only missed the target with one (not including the 14 blocks Leicester made).
Cazorla completed 71 of 77 passes (92 percent), created five opportunities for teammates, and assisted on Walcott's opening goal. Özil connected on 54 of 59 passes (also 92 percent), also created five scoring chances for teammates, and delivered a delicious cross for Alexis's second goal.
Leicester tried but could not match the Gunners' effectiveness in attack. The Foxes took 16 shots of their own, 11 in the Arsenal penalty area, and opened the scoring in the 13th minute when Jamie Vardy latched on to a long clearance, outran Per Mertesacker, and finished past Petr Cech into the far corner.
This set the tone for a wide-open match, which played to Arsenal's strengths.
Alexis loves Leicester
The King Power Stadium in Leicester will hold fond memories for Alexis when he ends his time in the Premier League.
Arsenal's star man got his first league goal there last season and ended his early season drought there Saturday with goals of opportunism and top quality.
His first was a welcome, straightforward finish, thanks to Walcott's clever run to the near post, which took two Leicester defenders with him. When Hector Bellerin's cross was redirected by that three-player melee, Alexis found himself with the ball in front of an open goal. The easiest of putaways got him off the mark for the season.
For his second, he received another pass from the marauding Bellerin, passed to Özil across the top of the Leicester penalty area, timed his run to escape all the defenders, then redirected Özil's cross past the onrushing Leicester keeper Kasper Schmeichel.
He capped the hat trick with a screaming low shot from outside the penalty area, an opening he generated himself with a deft flick of Nacho Monreal's throw-in past Leicester's Ngolo Kanté.
These were a worthy payoff for Alexis's combination of creativity, desire, and skill that took him to such heights in his inaugural Premier League campaign.
Nacho Monreal may be the best left back in the Premier League
It's a variation of the rags-to-riches story. Monreal joins Arsenal in January 2013, primarily due to the injury of starting left back Kieran Gibbs. The Spaniard does not thrive under the circumstances but gradually learns the requirements and tricks of a Premier League defender.
Watch the recent interview on the club's website for Monreal's thoughtful reflection on his career.
He's now made 94 appearances for Arsenal; his latest was an absolutely top performance against the league's in-form attacking player, Leicester's Riyad Mahrez.
Mahrez came into the match with five goals and three assists in six games this season. Monreal shut him out on Saturday, so much so that Mahrez switched sides to try to find better opportunities on Arsenal's right.
Overall, Monreal made seven ball recoveries, succeeded on seven of the eight clearances he attempted, and won seven of eight aerial duels. He also assisted on Olivier Giroud's goal in second half injury time, taking advantage of the flagging Leicester defense to reach the by-line and cut the ball back for the Arsenal striker.
That closed Monreal's outstanding display and solidified his place as the top left back in the league at the moment. Name a better one.
This was Walcott's top showing as a center forward for Arsenal.
The conditions favored him: Leicester's lumbering center backs and assertive defensive line gave him the space to use his speed. He did that, connected with Cazorla's defense-splitting pass, and delivered a subtle left-footed finish for Arsenal's first goal.
On other occasions, Walcott created space for teammates with intelligent runs, such as the one that freed Alexis for his opening goal. And he held his own in the physical battles.