With 79 minutes on the clock and a goalless draw looking the most likely outcome, the midfielder won the ball just inside West Ham's half and carried for 20 yards before chipping delightfully over Jimmy Walker from 25 yards.
It was a goal worthy of winning any game and secured an 11th win in the last 12 outings for Clive Allen's men.
Further good news saw the return of Dean Marney off the substitutes' bench for the final half-hour - his first action since rupturing his Achilles at the end of October.
And the night was completed when news of a defeat for nearest title rivals Arsenal against Fulham filtered through to Stevenage - leaving us 10 points clear at the top of the Barclays Reserve League South having played a game more than the Gunners.
Youth again played a big part with Academy players Alex Smith, Joe Martin, Stuart Lewis and Jamie Davis all in the starting line-up.
With a lack of strikers at his disposal - top scorer Lee Barnard and Simon Dawkins both injured - Clive opted to go with Andy Barcham up front on his own in a 4-5-1 system. Barchy rightly won plaudits for his tireless display up against two giant central defenders in Elliott Ward and James Collins.
Chances were few and far between in a cagey start until Barcham tested Walker for the first time after 27 minutes.
That triggered a fine spell for the rest of the half with Charlie Daniels and Tom Huddlestone firing just wide and Walker at his best to deny Huddlestone and Jackson. At the other end, Reid forced the ever-reliable Radek Cerny into a routine save to his left after a run and shot.
If we created more chances, West Ham certainly missed the best of the game six minutes into the second half.
Cerny dived out bravely to try and cut out Reid's cross from the right and the loose ball fell at the feet of Carl Fletcher just six yards out with Cerny still on the floor - incredibly, the midfielder fired over.
We continued to edge the chances in an open game as Daniels glanced a header just wide and Walker got his angles right to block Martin's effort.
When Calum Davenport - another impressive performance in central defence - leapt to meet Jackson's corner only to see it hacked off the line after 73 minutes it looked like being one of those nights.
Thankfully, Jackson had other ideas - the perfect goal for just about the perfect night.
GUIDE TO THE ACTION
16mins: Our first effort on goal as Daniels broke from midfield only to scuff shot at Walker.
17mins: West Ham straight up the other end and Davenport needed saving tackle to stop Collison in his tracks, Reid onto loose ball and curled wide from 25 yards.
23mins: Best chance so far, Dailly fizzed pass into Epraim who controlled, turned and shot straight at Cerny from 14 yards.
26mins: Collins dragged free-kick wide from edge of box.
27mins: SAVE. Barcham latched onto Collins' poor header back, ran at Ward, shifted ball left of the defender and shot low - Walker there to block with legs.
32mins: Barcham released Davis, he opted to play back to Barcham who controlled and laid back for Daniels to shoot just wide from 20 yards.
34mins: SAVE. Walker there again as Jackson forged his way into box, struck low right-foot shot that keeper did well to parry to his right, Barcham might have been first to loose ball but stumbled over and it was cleared.
37mins: Reid intercepted Lewis' pass in own half, sprinted forward fully 50 yards before hitting decent shot that Cerny took comfortably diving to his left.
39mins: Huddlestone effort from 30 yards forced Walker to tip wide at full stretch.
43mins: Huddlestone curled free-kick from edge of box inches wide.
Half-time: Spurs 0, West Ham 0
46mins: Fletcher whipped in low corner to near post sliced towards his own goal by Daniels but Cerny alert to save on goal line.
51mins: MISS. Reid whipped in cross from right, Cerny out amongst the studs to try and take it but ball fell to Fletcher six yards out, open goal - somehow sliced it over.
54mins: Barradji snap shot from 25 yards seemed to catch Cerny wrong footed but keeper recovered to take ball cleanly.
59mins: Good play between Barcham and Davis down right, Davis early cross met by Daniels, header across Walker but just wide.
62mins: SUB. Dean Marney into the action, his first game since rupturing his Achilles in October.
65mins: Daniels worked opening for Martin who had Collins tugging at his shirt but managed to get shot off from tight angle taken by Walker at near post.
73mins: OFF LINE. Jackson's corner met by Davenport's towering header, Walker beaten but Barradji there to hack off line.
79mins: GOAL. Moment of magic from Jackson - won ball in midfield and carried for 20 yards before delightful chip over Walker from 25 yards. 1-0.
Result: Spurs 1, West Ham 0
Line-ups: Spurs: Cerny, Smith, Martin (Maghoma, 72), Lewis, Davenport, Bunjevcevic, Davis (Marney, 62), Huddlestone, Barcham, Jackson, Daniels. Subs: Hughton, Burch, Kyriacou.
West Ham: Walker, Dailly, Clarke (Blewitt, 62), Collins, Ward, Fletcher, Collison (Welsh, 74), Barradji, Katan, Ephraim (Hines, 83), Reid. Subs: Blackmore, Cowley, Tomkins.
A moment of magic from Johnnie Jackson clinched a vital 1-0 win for our title-chasing reserves against West Ham on Monday night.