A Gary Charman header and two James Fraser penalties put Bognor back on top of the Ryman premier - and set up a cracker of an Easter Monday title showdown at Havant.
Harlow had two men sent off and never really looked in the game once they had gone behind midway through the first half, and by the end the scoreline could have been much bigger.
It means Bognor head for west Leigh Park one point in front of Havant and with a goal difference that's superior by three.
Havant's Good Friday win at Canvey Island by 2-1 had put them two points clear of the Rocks at the top, so the onus was on Bognor to get a similar result, or face having to travel to West Leigh Park on Monday with their hosts still in first place.
James Crane was back in the Bognor squad after a spell away with work but had to be content with a place on the bench. Gary Charman got the nod in injured Dan Beck's No8 shirt.
The Rocks knew they would not be in for a straightforward afternoon: although Bognor went into the game top of the past-six form table, Harlow were not far behind in third place.
After a minute's silence for ex-Rocks player Brian Holly, Bognor kicked off on a sunny but blustery afternoon and soon launched the first attack but Dylan Barnett's low ball in from the left missed everyone.
Jimmy Muitt's persistence down the right won the first corner in the fourth minute, but it came to nothing despite shouts for a Harlow handball.
It took the Rocks a while to build another attack of note but when they did Muitt flashed a 20-yard shot across the goalmouth and wide, with one or two team-mates not far off getting a touch as it went out for a corner.
Both sides were struggling for any fluency and each goalkeeper was having a quiet time. A surging run by James Fraser released Jimmy Wild in a good position in the box but he delayed his shot and it was cleared for a corner.
Harlow's Stan Muguo was booked for dissent - and he had something else to complain about when the corner came over from Barnett and it was headed in six yards out by Charman with 23 minutes on the clock.
That brought Bognor to life and Fraser and Whyte led another attack that was halted by a foul on the latter. Barnett curled the free-kick towards the bottom corner but keeper David Hughes got down to it.
Harlow briefly threatened when ex-Reading, Stoke and Pompey defender Ibrahima Sonko flicked a near-post header just wide from their first corner.
Sami El-Abd suffered a nasty gashed forehead when he went in to head a ball clear and was caught by a high boot by Bamba Ngamb. The offender was booked as El-Abd was treated, with blood gushing from the wound.
Muitt led another attack with a run of all of 60 yards and played in Fraser, who just took it too wide and saw his shot easily saved. To Bognor's relief, El-Abd had been bandaged up and was back among the action.
Before long, Ngamb was on his way to the dressing room - picking up a second yellow for a foul on Doug Tuck as he ran on to his own headed clearance to try to launch a forward move.
A nice move from a throw-in on 45 minutes led to Tuck floating a cross that Muitt hit sweetly on the volley but it flew wide.
Things got better for the Rocks in first-half stoppage time when Muitt got into the box down the right and pulled a pass back for Fraser, who was brought down by Sonko as he tried to take it past him. Fraser put away the spot-kick himself.
The start of the second half was fairly pedestrian and Rocks physio Rachel Rees was busier than most of the players. First she had to attend to El-Abd a second time after his bandage came off - then she was on to treat Charman after he and Muguo kicked each other's boots in going for a 50-50 ball, both going down in agony.
Whyte was booked - seemingly for dissent - after a free-kick was given against the Rocks as they went in search of a third.
Harlow brought on Syrus Gordon in place of Muguo, while the Rocks introduced Ollie Pearce for Charman.
Muitt almost got a third from way out wide when he battled to the by-line and saw his cross shave the top of the bar. Then Pearce's cross was plucked out of the air by Hughes just as Muitt lurked.
Whyte and then Muitt both looked in on goal in a quick Rocks break on 69 minutes but the Harlow defenders got back in numbers to concede a corner.
It was 3-0 on 76 minutes - and 2-0 to Harlow in red cards. Pearce's run was curtailed just inside the box and a penalty was awarded. As Fraser waited to take it, Dadson was booked - then talked himself into a second booking and was shown a red card.
He didn't want to go off and when he did, he had to be hurried along by his own team's backroom staff and then, after sitting in the dugout, he was shown to the dressing room by the Nyewood Lane stewards
Both sides made changes - Harlow bringing on Jack Curtis for Fabian Simms and the Rocks replacing Muitt and Fraser with Darren Budd and James Crane.
Harlow threatened as they hit the post in a goalmouth scramble but that was a rare venture into the Rocks box for them.
A final Harlow change saw Tommy Fagg come on for Alex Read.
The Rocks looked in for a fourth on 87 minutes as Whyte played Pearce in on Hughes but his shot was weak and easily gathered.
Whyte then should have made it four but curled a right-footed shot just wide from 15 yards.
Even into stoppage time, the Rocks kept attacking but a fourth goal wouldn't come. But that mattered little as the home fans and players celebrated a crucial win that sets up the trip to Havant nicely.
Rocks: Lincoln, Davies, Barnett, Tuck, El-Abd, Field, Fraser, Charman, Muitt, Wild, Whyte. Subs: Budd, Beck, Pearce, Crane, Dolcetti.
Harlow: Hughes, Small, Eadie, Pope, Sonko, Muguo, Ngamb, Simms, Read, Noto, Dadson. Subs Dickens, Gordon, Fagg, Curtis, Lee.
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