The Islanders, who had previously won only twice in 12 home Conference starts, could hardly have made a better start.
Canvey took a fifth minute lead when, after appeals for a penalty when Neil Midgley went to ground were turned down, the ball broke to skipper Neil Gregory who volleyed home a left-foot effort from the right-hand side of the box.
Three minutes later, and to the delight of the home supporters, it was 2-0. John Keeling's corner from the right saw on-loan striker Greg Pearson rise to send in a close-range header which visiting goalkeeper Tony Roberts could only parry.
But he was powerless to stop the unmarked Ollie Berquez lashing home the rebound. It was a third goal in two games for Berquez who, like Keeling, is an ex-Dagenham man.
Canvey had the ball in the net again on the half-hour, Gregory heading home Keeling's cross, but the effort was disallowed for offside.
As in the first-half, Canvey were the dominant force as the second period got underway - forcing three quick corners.
And they made the pressure tell after 55 minutes. Skipper Gregory, enjoying a great game despite not being fully fit, put Chris Duffy clear on the left with a superb flick and the wing-back's cross was dispatched to the back of the net by Midgley.
In front of their biggest home crowd so far this season, 1,309, Canvey looked very much favourites for the three points at this stage.
However, all this changed when Daggers pulled back a goal in very fortunate circumstances when substitute Mark Janney, having forced a corner, shot wildly but saw his effort, which was going well wide, deflect off home defender Dominic Sterling and into the net.
That was after 76 minutes and 60 seconds later it was 3-2. Another corner, taken by Glen Southam, saw another substitute Steve Clark knock the ball across goal for Jake Leberl to head home.
Amazingly it was soon 4-2 with the third goal in four minutes. Keeling's corner was headed back by Dave McGhee and ex-Dagenham striker Junior McDougald, who had replaced hero Gregory six minutes earlier, was on hand to shoot home.