Naismith on the spot as Luton battle to a terrific win over play-off rivals Forest
The visitors had rocked up at the ground on a lengthy 10 match unbeaten run, which included five straight wins, and seven victories in total, as they still had dreams of catching second-placed Bournemouth.
However, as they have done this term, Luton saved their best for matches against the top sides, as following a draw with Fulham and beating the Cherries on home soil, Nathan Jones' side, with Allan Campbell in particular giving a sensational lung-busting display, ended their own mini blip of sorts thanks to Naismith's nerveless spot-kick.
They even had to play the last 13 minutes with 10 men after Sonny Bradley's controversial red card, but to a man they put their bodies on the line to hold off the Reds in what was a frantic conclusion, played out with a packed out stadium roaring them on.
Jones made two changes to the side who faced Huddersfield Town on Monday night with Pelly-Ruddock Mpanzu and Henri Lansbury absent as expected, following their knee and neck injuries picked up in the 2-0 defeat.
Robert Snodgrass came in for his first start, while defender Reece Burke was also back after missing four games due to a hamstring injury, Elliot Thorpe on the bench too.
The Hatters moved Fred Onyedinma to a new position as left wing-back, James Bree right, with Kal Naismith holding in front of a defence of Burke, Sonny Bradley and Amari'i Bell.
A fast opening by the hosts, who pressured their opponents into some uncharacteristic mistakes in front of a fully invested and vocal home support saw Onyedinma almost give them the perfect start, as Bradley's low, flat ball out from the back was miscontrolled by Djed Spence, the winger's toepoke deflected behind by Brice Samba.
Forest then showed signs of their undoubted class, on-loan Aston Villa forward Keinan Davis, bizarrely in gloves, setting off on a muscular run to find his strike partner Lewis Grabban, whose low shot looked destined to break the deadlock, only for James Shea to get down superbly to palm it behind for a corner.
Luton were back on the front foot though, once more causing the Reds to misplace a number of passes, with the willing Onyedinma always an out ball, as after winning another corner, Naismith's 30-yard blast flew over the top.
Forest began to get a foothold though, breaking Town's press with more regularity, but the best they could muster was a Grabban effort that was never testing Shea.
With 37 minutes gone, the Hatters were then handed, quite literally, the chance to open the scoring when a long ball from defence was collected by Bree, with Jack Colback unable to keep his arms down, the linesman signalling the offence and referee James Linington pointing to the spot.
It completed a miserable season against the Hatters for the former Sunderland and Newcastle player, who had hauled Tom Lockyer down at the City Ground for a penalty that Brice Samba went on to save from Elijah Adebayo.
With that in mind, and after his miss against Huddersfield on Monday night, Naismith assumed responsibility, grabbing the ball and this time Samba was unable to be the hero, the Scot calmly sending him the wrong way to make it 1-0.
It had looked like Forest were on level terms just moments after the break, Spence going through to beat Shea but once more Town were grateful to see the linesman's flag raised as it was ruled out for offside.
Adebayo had a sniff of a cheeky second when the visitors defence gave the ball away, but his snapshot lacked height and power to beat the back-pedalling Samba, who was able to control easily.
Luton really should have further the lead on 66 minutes though when Snodgrass sent over a corner, an unmarked Naismith heading down and over the bar when she should have tested Samba.
They were almost made to pay immediately as a neat move by the visitors saw sub Philip Zinckernagel, left all alone and with his first touch, put his header too close to Shea who gratefully clung on.
Forest kept the momentum up though, Spence finally getting on the outside of Onyedinma, his low ball skied over by Ryan Yates.
The game took another twist with 15 left as Town were reduced to 10 men when Bradley was shown a second yellow for clipping sub Sam Surridge, the forward clearly in an offside position, but the referee believing it touched a Luton player on its way through to him.
The wall did its job from Zinckernagel's free kick, as somehow it remained 1-1 moments later, when the same player curled against the post, Shea at full stretch to save from Spence's follow-up.
In the build up, Davis pulled up and had to go off which meant that with Forest out of substitutes, the numbers were crucially evened up for the final eight minutes.
Adebayo almost made the points safe, creating some space before shooting against Samba's legs, as eight minutes of stoppage time were flashed up, but the closest the Reds came was that man Zinckernagel again, shooting wastefully over from outside the box.
Hatters: James Shea, Fred Onyedinma, Amari'i Bell, James Bree, Reece Burke, Sonny Bradley (C), Kal Naismith, Robert Snodgrass (Peter Kioso 82), Allan Campbell, Harry Cornick (Danny Hylton 65), Elijah Adebayo (Tom Lockyer 90) .
Subs not used: Harry Isted, Elliot Thorpe, Admiral Muskwe, Dan Potts.
Reds: Brice Samba, Djed Spence, Tobias Figueiredo, Joe Worrall, Lewis Grabban (C, Sam Surridge 75), Jack Colback (Joe Lolley 81), Keinan Davis, Brennan Johnson, Ryan Yates, Scott McKenna (Philip Zinckernagel 66), James Garner.
Subs not used: Ethan Howarth, Richie Laryea, Alex Mighten, Cafu.
Bookings: Bradley 26, Garner 44, Naismith 48, Burke 63, Davis 63, Campbell 63, Shea 70, Worrall 74, Adebayo 90, Figueiredo 90.
Sent off: Bradley 77.
Referee: James Linington.
Attendance: 10,070 (1,031 Forest).