Gulls were never really troubled by their opponents who currently top their league and threatened to run riot by scoring early and creating numerous chances.
Right from the first whistle, Canvey were a threat and just 90 seconds had passed on the clock when Alex Rhodes surged past Bradley Stopher as he cut into the penalty area from the left but he dragged his shot across goal and wide.
Jason Hallett then came close a minute later as he twisted and turned in the area but fired just wide of Danny Sambridge’s goal.
The deadlock was broken moments later though when Andrew West and Leon Gordon combined down the right and Danny Heale was left in acres of space to head home the cross.
The Witham defence was struggling to contain a Canvey side who were passing the ball around nicely and showing some good movement. Rhodes curled a low shot wide from the edge of the penalty area on 14 minutes and Sambridge was down well to save an effort from Robbie King but a second goal looked inevitable.
This came on 24 minutes when Jason Hallett latched on to a bouncing ball into the penalty area by Gordon and guided a back header over Sambridge and into the top corner of the net.
Canvey’s attacking momentum was curtailed slightly when both Steve Ward and Rhodes were forced off with injuries before half time. Michael Alaile and Jamie Matthews replaced them and these enforced changes seemed to upset Canvey’s rhythm slightly with Witham coming gradually more into the half.
They were rarely a threat though and with John Easterford and Alaile strong at the back, Andre Foster in the Canvey goal was rarely tested.
The second half was a more disjointed affair with Canvey struggling to play the passing football they had demonstrated before the interval.
Witham had decent spells of possession but again were rarely able to turn this into genuine clear-cut opportunities and for the most part, Gulls looked quite comfortable.
On the break, Canvey always looked a threat and this was evident on 67 minutes when Hallett broke down the left and laid the ball across goal for Gordon who was sliding in at the far post but under pressure from the defender he could only guide the ball wide.
A third goal sealed the victory for Canvey on 71 minutes. After a foul on West near the right touchline, Ashley Dumas whipped in a superb free kick that Heale headed home at the far post.
Jay Curran replaced Hallett with 12 minutes to go and the striker helped set up an opportunity for King but his half volley from just inside the penalty area was brilliantly turned away for a corner by Sambridge.
Foster was finally tested on 83 minutes when he produced a good reflex save to deny Daniel Lopes after the striker found space in the penalty area and fired in a volley.
Canvey concluded the scoring on 88 minutes with a 4th goal. Matthews and Dumas exchanged passes down the left and Dumas was able to play in a superb cross that picked out Easterford in the centre who had all the time in the world to head home from a couple of yards out.
The final whistle blew moments later and Gulls now eagerly await the semi final draw where they could potentially meet Island rivals Concord Rangers.