After an even opening half hour where both sides defended well, limiting each other to half chances, the Millers took the lead in the 33rd minute through Wiggins.
Having begun to get a foothold in the tie, Aveley forced a corner when Mead cut back for Ace whose shot was blocked.
The resulting corner was whipped in towards the far post and headed away, but only as far as Wiggins who volleyed the ball in at the near post to give the home side the lead.
Their jubilation though wasn’t to last very long as within two minutes Hornchurch equalised when Daniel Boyce was sent clean through.
Levey in the Millers goal came out bravely to dive at the feet of Boyce, but could only deflect the ball in off the forward to level the cup tie up before the break.
The 1-1 score line was arguably a fair reflection on the first half display from both sides, after the Millers had soaked up pressure early on before taking the lead.
Early in the second half and Wiggins, who had been a constant threat up front for Aveley, had a great chance to put his side back in front when he was sent clean through only for the Hornchurch ‘keeper to claim at his feet.
And it was a chance that the Millers were almost made to pay for as Hornchurch hit the post from a couple of yards out moments later before they put one just wide after a cross from the left.
Wiggins then had another effort which he dragged harmlessly wide before good defending by Mead prevented Harry Catherall getting in on goal.
But after defending so well against the diminutive Catherall moments before, a slip by Mead allowed the winger in to slide one past Green and give Hornchurch the lead for the first time in the match with 15 minutes remaining.
The goal rocked the Millers as Hornchuch pushed for a killer third, creating two chances in quick succession which they were unable to take.
And with Aveley throwing everything forward in search of an equaliser the Urchins broke to seal victory and a place in the final through George Brooker.
A long ball from the back left Brooker one on one with Green. The goalkeeper hesitated just enough to let Brooker get to the ball first, allowing him to loop it towards the unguarded net and send his side through.
In the final seconds Kimble did hit the post for Aveley deep into injury time with an effort from inside the box, but it would have been too little too late had it of gone in, as Hornchurch advanced to face Tilbury in the final.