The former Brighton man, on as a substitute, stabbed home amid a goalmouth scramble deep into five minutes of stoppage time to send 1,957 travelling Town fans wild as the unbeaten run was extended to 12 league matches.
Including FA Cup, that sequence is 14 games, with James Collins having moved into double figures for the season with a 72nd-minute goal, after a first-half penalty from Morgan Ferrier and a second-half strike from Andy Cook had seemingly put the Saddlers in control.
But with Danny Hylton introduced as a substitute for the injured Harry Cornick before half-time, then LuaLua and captain Alan Sheehan - who last combined as game changers to produce a win at Oxford a couple of months ago - in the closing stages, the depth of the Town squad was there for all to see.
Manager Nathan Jones made one change to his starting line-up, with Alan McCormack, who appeared as a second-half substitute in the 2-0 Boxing Day win at Scunthorpe, coming into the side in place of Jorge Grant. The Irishman would play a crucial part too, lasting the full 90-plus minutes and producing two assists in the comeback.
Jones started with James Shea in goal, Jack Stacey, Matty Pearson, Sonny Bradley and James Justin at the back, with McCormack, Pelly-Ruddock Mpanzu, Andrew Shinnie and Elliot Lee in midfield, behind Collins and Cornick up front.
The second-placed Hatters were chasing an eighth successive victory in the league - ten including FA Cup - against a Walsall side who sat 14th at kick-off.
The Hatters enjoyed the majority of the early possession without making too many inroads into the Saddlers' defence, until the 18th minute when Shinnie and Cornick combined with Lee to set the top scorer up for an 18-yard blast that Liam Roberts did well to tip over the bar.
Walsall responded with Cook sending a tame header straight at Shea, before the Town came within a lick of paint of taking the lead, as Mpanzu curled a beauty around Roberts, but it hit the top of the post and bounced away to safety.
The hosts made the breakthrough in the 26th minute when Stacey brought George Dobson down as the Walsall captain headed towards the left byline, and Ferrier did the rest from 12 yards.
The Hatters forwards had taken a bit of a battering early on, especially Lee who had been injured when striking at goal. Cornick was next to pick up a knock, to his thigh, and Jones took the precaution of substituting the forward to bring on Hylton in the 35th minute.
There was no way through ther home defence in the remaining ten minutes of the half, so Jones' side were in the unusual position of going in at the break without a lead for the first time in ten matches.
They came out of the traps quickly in the second period, winning a couple of early corners and dominating possession once again, without creating any clear-cut chances.
McCormack became the first Town player to go into referee Ollie Yates' notepad on the hour for a foul on Gordon, who had just been booked for a foul on Mpanzu, then Hylton joined them within seconds for a foul on Nicky Devlin as he challenged for a high ball.
Jones made his second sub of the afternoon on 63 minutes, bringing on Kazenga LuaLua for Lee, but Walsall doubled their advantage in the 68th minute when Shea could only palm a Luke Leahy cross towards Cook, who volleyed it straight back past the Town keeper from beyond the far post.
Four minutes later the Hatters were back in business. McCormack picked the ball up in his own half and made his way forward, trading passes with Hylton and driving towards the edge of the box. The Irishman let fly and the ball landed at Collins' feet, with the striker spinning and firing past Roberts from 15 yards.
Jones immediately introduced Sheehan for Shinnie, with Justin moving into midfield, and two minutes later the ball was in the back of the net again as Hylton turned Mpanzu's 20-yard volley into the far corner, but a linesman's flag was raised for the striker standing in an offside position - though replays showed he was well onside.
The Town had set up camp in the Walsall half by this stage, and LuaLua was the next to have a go, drifting in from the left flank to unleash a right-footed shot that flew wide of Roberts' left-hand post.
The next opportunity fell to Justin 20 yards out, after Sheehan's left-wing cross had been headed half-clear, but the 20-year-old's shot was dragged well wide.
Town have that belief that they are never beaten, however, and four minutes into injury-time the equaliser finally came. With Bradley playing as an auxiliary striker, balls were thrown into the box and after a Sheehan free-kick was headed behind for a corner, they made the breakthrough.
Sheehan went over to take the left-wing corner, and after Hylton and McCormack had challenged in the air, the ball dropped amid a six-yard box scramble and LuaLua hooked it in from close range.
The players disappeared into the travelling Hatters over on the far side, and wild celebrations ensued. Now it's back to Kenilworth Road for a full house on New Year's Day against Barnsley, the last side to beat the Town back in mid-October.
Have a happy new year, Hatters!
TOWN: Shea, Stacey, Pearson, Bradley (c), Justin, McCormack, Shinnie (Sheehan 72), Mpanzu, Lee (LuaLua 63), Collins, Cornick (Hylton 35). Subs: Berry, Grant, Jones, Isted.
Yellows: McCormack, Hylton, Collins
Goals: Collins 72, LuaLua 90+4
WALSALL: Roberts, Edwards, Leahy, Dobson (c), Guthrie, Devlin, Cook, Kinsella, Ferrier, Fitzwater, Gordon (Wilson 80). Subs: Dunn (GK), Morris, Ismail, Johnson, Ronan, Bates.
Goals: Ferrier (pen) 26
Yellows: Gordon, Guthrie
REFEREE: Ollie Yates
ATT: 5,739 (1,957 Hatters)
