Chichester set a first XV record for the past decade with their tenth straight win from the start of the season - the latest a 23-13 success over Wimbledon in London one south.
It was a deserved result after a tough battle with the Dons for vital points but the Blues were narrowly denied a bonus for the first time this campaign.
They are second to East Grinstead, who have the same number of points, and the two clubs meet in the next game.
Chichester had much the better of the first half and the second was fairly even. They shared possession in the tight but their forwards were sharper in the loose and their back row was a constant threat.
Richard Adams had a fine game at fly-half and was involved in each of their scores.
Jack Bentall and Joe Woods were injured but Chris Johnson and Tim Cook returned. Ex-Premier player Lawrence Marsh and Colts graduate Henry Luxton made their home debuts.
A large crowd had assembled and an early penalty gave a lineout chance but the throw was crooked. Full-back Toby Golds tackled out the Dons right winger, who had taken a slick pass from fly-half Hallett.
Hallett slotted a penalty after 15 minutes after even exchanges.
The Dons messed up a certain try when their centres broke through but the final pass was wild.
Chichester found their rhythm and Johnson made a thrust from the back of the scrum, followed by a scintillating Adams break and pass which put Luxton almost over. The Dons scrum-half dived over the ensuing ruck and was sin-binned, Adams kicking the penalty.
The Blues cut loose with Aaron Davies, Billy Toone, Tom Jackson ,Golds and Adams combining. The attack continued across the pitch and back for Adams to slip a pass to hooker Gray to find the gap in the centre and score the first try. The conversion was slotted by Adams. Hallett replied quickly with a penalty.
Another Chi raid caught Dons offside but this time Adams missed a fairly easy kick. He made up for it with a brilliant break, evading three tacklers and setting up the ruck from which Toone scampered across to touch down. But play was brought back because the referee had got in the way.
Moses Kasujja carried strongly and the ball went to Adams, who pivoted and sent a perfect high kick to the right wing. Tall Sam Renwick was in the right place to catch above his head and dive over. The conversion drifted just wide. At half-time it was 15-6.
Chi restarted in determined mood, Toone sidestepping and prop Phil Veltom using his strength.
Golds made a half-break and a penalty was sent into the corner. The lineout was lost and the chance went begging. Dons started to move towards the Chi 22 with solid mauls anrd rucks. Chi’s defence was firm with captain Ben Polhill pulling the strings.
Suddenly Hallett seized the ball from a breakdown on his own 22 and bolted up the right touchline. Adams raced back and stopped his opposite number.
A lineout was pinched from a Dons throw and Kasujja, Cook and Luxton set up second phase. Golds hurtled into the centre of the line but knocked on.
Dons also knocked on in a useful central position as the tension caused some scrappy play.
The crowd roared as Toone went dancing with sidesteps and jinks, finishing with a pass to Luxton for another run towards Vultures’ Corner. Veltom, Polhill and Kasujja were the Three Musketeers in suport and they combined cleverly to go the last ten metres for Kasujja to crash down for a 20-6 lead.
The Dons exerted more pressure until Veltom was given a yellow card for not releasing a tackled player at a ruck. Dons took advantage and quick hands put winger Palakua on course to the right corner.
Golds and others were sure his tackle knocked the ball out of his hands as he dived, but the try was awarded and converted by Hallett from the touchline.
Dons missed a last penalty which would have given them a losing bonus point and Chichester went to the other end for Adams to seal the victory with a 35m penalty.
Could the get the bonus? In the last minute Johnson charged through and was brought down by a last-ditch tap tackle just two metres out. So near, so far.
Director of rugby Paul Colley said: “It was a pleasing result. It might have been a bigger margin but I don’t think we had the rub of the green with some of the decisions.”
November 17 at East Grinstead is the big one against the semi-professionals who have averaged nearly 60 points a game. All support needed.
CHICHESTER: Shopland, Gray, Veltom, Davies, Goldie, Johnson, Polhill, Kasujja, Toone, Adams, Luxton, Cook, Renwick, Jackson, Golds, Marsh, Taylor, Corrigan.