Millwall's very own brand of Special K served up a goal double to secure Championship football at The Den for another season.
Goals in either half from Harry Kane (22mins) and an Andy Keogh penalty (54mins) put The Lions 2-0 ahead, and although Foxes sub Danny Drinkwater reduced the arrears nine minutes from time, Kenny Jackett's side held on for a victory that sparked wild celebrations at the final whistle.
"It was very important to preserve our Championship status," beamed boss Kenny Jackett.
"Thankfully we found form, results and a way of winning. We tried to have a settled side and I must say, the Keogh and Kane partnership has worked for us up front, but this was a real hard-working performance again and we deserved to win."
And no one player expressed the sheer relief and raw emotion of that win more than skipper Paul Robinson, who led by example and was quite simply magnificent throughout.
It was a fast and furious game that at times had more of a Cup-tie feel to it, as both teams went about their business with real urgency from the opening minute.
Leicester certainly enjoyed the best of the opening exchanges and caused some anxious moments early on when Ben Williams, twice, and Lee Peltier despatched inviting deliveries that were blocked as Millwall's resilient rearguard proved impenetrable.
However it was Millwall who struck first on 22 minutes with Kane's third goal in successive games. James Henry sent in a deep free-kick from the right, Robinson headed back and young striker Kane showed great composure, taking a touch to control the ball before hitting a rasping, rising shot that flew into the roof of the net.
However, Leicester were denied an equaliser almost immediately, when Wes Morgan directed Marshall's pass into the path of David Nugent, who was brilliantly denied by Maik Taylor in the home goal.
At the other end it took a perfectly-timed tackle by Sol Bamba to nick the ball off the toes of Kane as he streaked through after picking up a long clearance from Shane Lowry.
The visitors, who had Play-Off aspirations of their own heading into this game, were left a mountain to climb nine minutes after the break as The Lions doubled their tally. Some fine interplay between Keogh and Kane ended with the latter clattered by Paul Konchesky, and referee Phil Gibbs had no hesitation in both brandishing a yellow card and pointing to the spot.
Despite Henry's attempts to persuade Keogh that he should take the penalty, former Wolves frontman Keogh was having none of it and promptly added to his spot-kick conversion against Hull City last Saturday with another clinical finish that gave Kasper Schmeichel no chance in the Leicester goal.
The visitors introduced Lloyd Dyer, Drinkwater and Steve Howard in a bid to shake things up, but Millwall dealt confidently and competently with everything that Leicester threw at them.
It took a fingertip save by Schmeichel to somehow divert Josh Wright's magnificent dipping volley onto the bar as Millwall looked for a third goal.
But credit to the visitors who kept plugging away and grabbed a lifeline nine minutes from time courtesy of Drinkwater's crisp drive after Nugent had teed him up on the edge of the penalty area.
A last-gasp tackle by Robinson averted the danger as Jermaine Beckford broke clear right on the 90th minute as Leicester piled on the pressure in search of an equaliser
The final five, nervy minutes of injury time saw The Den faithful once again come into their own, creating a deafening wall of sound to urge, encourage and eventually help the players to the full-time whistle and over the finishing line.
There may be three games left this season, but come August, Millwall will be back playing Championship football once again - and the supporters should take a bow for playing such an important role in making sure that happened.
Millwall: Taylor, Smith, Craig, Abdou, Robinson, Lowry, Barron, Wright, Keogh (Batt, 90+3mins), Kane, Henry (Trotter, 83mins). Subs not used: Forde, Dunne, Feeney.
Booking: Lowry (60mins)
Scorer: Kane (22mins), Keogh (54mins, pen)
Leicester City: Schmeichel, Peltier (Howard, 76mins), Konchesky, Bamba, Gallagher (Dyer, 57mins), King, Wellens (Drinkwater, 68mins), Beckford, Marshall, Morgan, Nugent. Subs not used: St Ledger, Schlupp.
Bookings: Konchesky (54mins), Peltier (64mins)
Scorer: Drinkwater (81mins)
Ref: P. Gibbs
Att: 11,525 (away 1,400)