Manager Brendan Rodgers made six changes to his side for the clash with the Seagulls, with Kasper Schmeichel, Christian Fuchs, Marc Albrighton, James Maddison, Ayoze Pérez and Jamie Vardy - making a Club-record equalling 222nd appearance in the Premier League - all returning to the starting XI.
An effort inside 120 seconds was sent over the crossbar by Wilfred Ndidi as the Foxes attempted to grab an early goal on Filbert Way, before Mat Ryan held onto an Albrighton drive and Schmeichel denied Alireza Jahanbakhsh's low effort during what was a lively opening five minutes.
Denmark international Schmeichel was called into action again on nine minutes as he made a fine save with his legs to prevent Danny Welbeck converting from a one-on-one situation.
Both sides traded blows in the opening 45 minutes, with Jahanbakhsh firing well over before Maddison had a strike blocked by defender Lewis Dunk's mid-rift shortly before the first half's midway point.
City maintained their pressure and after Vardy had struck the upright from a tight angle, the hosts were ahead just seconds later as Maddison placed the ball into the bottom corner, past Mat Ryan, shortly before the half-hour mark.
It would have been 2-0 on 30 minutes were it not for a fine save from Ryan to prevent Pérez's low drive from finding the net following a lovely move from the Foxes.
But Leicester didn't have to wait much longer for their second of the night. Pérez played a role in the build-up, this time, as he found Justin, whose first-time cross was touched beyond Ryan by Vardy - a goal eventually confirmed by VAR.
There was still more to come from City before the interval. This time, Vardy pulled it back for Maddison, who worked it onto his left foot and unleashed an unstoppable curler into the top corner for his second of the game.
After Schmeichel held onto Neal Maupay's tame overhead-kick, Rodgers made his first substitution of the evening as Academy graduate Harvey Barnes replaced Pérez on 62 minutes.
It was Fuchs who next came close to extending Leicester's advantage, only for his powerful drive to be parried away by Ryan, who remained busy in the Brighton net.
A wayward strike from Ndidi followed the introduction of Dennis Praet in place of the magic Maddison, before the Nigerian's night came to an end with 10 minutes remaining, as he was replaced by Papy Mendy in a like for like change.
There was little to report in the closing stages though, and it was City's first-half ruthlessness that saw them claim a deserved home win.
Major moment
As both sides traded blows in the opening stages, the first goal of the game would be a decisive one, and that arrived on 27 minutes via the left foot of James Maddison.
His low shot had just enough power on it to beat Mat Ryan, while an instinctive finish from Jamie Vardy and Maddison's wonderstrike ultimately secured three Premier League points for the hosts.
Who impressed?
Speaking on LCFC Radio, Matt Elliott said: "It’s hard to pick one, but it’s hard to look elsewhere other than James Maddison, mainly for the pure quality of that second goal. James Justin also impressed me massively, and Marc Albrighton was an unsung hero, too. I’m tempted to go for one of those two, but I have to give it to Maddison."
Where do we stand?
After 12 Premier League matches, the Foxes sit third in the table following their convincing victory over Graham Potter's men.
They are now just one point behind leaders Tottenham Hotspur, who they face in a week's time in London.
Coming up…
A second Premier League home fixture in the space of just four days arrives on Wednesday, when the Foxes entertain Everton (6pm kick-off) before heading to Tottenham Hotspur Stadium to take on José Mourinho’s side on Sunday (2:15pm kick-off).
Spurs were held to a 1-1 draw at Crystal Palace in their latest outing, while on Saturday, Everton beat Chelsea 1-0 at Goodison Park.
All times GMT.