Jamie Vardy ended his recent goal drought by opening the scoring just after the 20-minute mark before Jonny Evans quickly doubled the Foxes' advantage with a header from a corner.
Kelechi Iheanacho then made it three with a close range finish nine minutes before half-time to ensure the game was well out of sight.
The victory takes Leicester four points clear ahead of West Ham United and Chelsea as the race for the Champions League spots hots up.
Story of the match
With lots to play for at either end of the table it was a lively start from both sides as they looked to find an early lead.
The in-form Iheanacho poached the ball away from Dara O'Shea before taking a heavy touch which allowed Sam Johnstone to slow the Nigerian down and block the effort.
The visitors just moments later had their own chance open the scoring through Mbaye Diange however his lack of composure denied him from making any real connection from close range following Mattheus Pereira's ball into the Senegal striker.
The Foxes were in control for the majority of the first 20 minutes, however they were only restricted to bit-part opportunities. Iheanacho again was the closest for Brendan Rodgers' side.
Timing his run to perfection, the top goalscorer jinxed his way through the defence before looking to pull back to a blue shirt in the box.
Moments later though and their dominance did pay off courtesy of Jamie Vardy.
A weighted through ball from Youri Tielemans slid found the run of wing-back Timothy Castagne who breezed pass the West Brom defence before rolling the ball across to Vardy who made no mistake, lifting the ball over Johnstone to net his 15th of the season.
Just three minutes later and Leicester made the Baggies pay once more for poor defending through defender Jonny Evans.
A whipped corner from Tielemans was flicked on and met by the head of the former Albion man who ran into the box free, to score his first goal since December 2019.
The goals had seemingly opened the floodgates and it was almost a third in five minutes.
Once again Castagne found himself in space and fired a low-driven shot towards goal however it could only bounce off the post before being cleared away to safety.
It was only a matter of when Leicester would add their third and 10 minutes before half-time was when they did.
Vardy's bursting run down the left hand channel towards the box left past the West Brom backline before cutting back to Iheanacho, who took time to take a touch and find his balance before slotting away to all but end West Brom's hopes of finding a way back.
Iheanacho then had the chance to add his second of the game after some lovely fluid football from the home side however after doing all the hard work to control the ball, the striker ballooned his effort from close range to sail over the bar.
The start to the second-half picked up where it had left off at the break, with the hosts creating the majority of the chances, however with the game already secured, there was more of a calmness about their play.
West Broom looked as toothless as they have done for most of the season, failing to test the resolve of Kasper Schmeichel with any real worrying efforts on goal.
Iheanacho had the chance to score again from a free-kick 78 minutes in after Ayoze Perez was brought down on the edge of the box by Kyle Bartley however his strike was well met by the gloves of Johnstone.
The remainder of the game saw no further chances with the East Midlanders keeping the ball to ensure their three-goal lead stayed intact.
Baggies look buried
After coming into the game off the back of two important wins which gave some hopes of survival, defeat at the King Power Stadium brought them back down to the harsh reality they face of securing survival.
From minute one, Sam Allardyce's side were second best and at times didn't even look interested as they allowed their opponents to play around them with ease.
With a nine point gap to 17th place and six games to go, it looks more and more likely that they will be playing in the SkyBet Championship next season.
Vardy finally ends goal drought
It's been an unusual run of form for Jamie Vardy of late but his goal tonight is a much-needed one.
The 34-year-old scored his side's first of the night to find the net for the first time since February and just his second in 20 games.
With a run of difficult fixtures to come for the Foxes towards the end of the season, there is hope that this is the return of the goal-scoring Vardy Leicester know.