City had to come from behind in the tie after Jack Munns had given Hornchurch the lead in the first-half. However, after the hosts' Tom Wraight was sent off for a crunching challenge on Jean-Baptiste Fischer, City turned the tie on its head to overpower their Isthmian Premier Division opponents.
Ross Jenkins opted to make one change from the side that drew 2-2 with Tonbridge Angels in Vanarama National League South, with Lewis Coyle replacing Lewis Miccio at left-back. Jenkins also handed U23's forward Jayden Carbon a place in the squad for the first time.
The first-half was a tightly-contested affair. Both teams battled for possession in the middle of the pitch and both were consigned to half-chances and speculative efforts at best.
It took until the 34th minute for there to be any chance of note and it ended with a goal. Hornchurch's Jack Munns found space inside the box after a corner and he made no mistake, firing into the roof of the net to the delight of the home fans.
Things were going well for the Isthmian League side but the game was turned on its head just before the interval when Tom Wraight was shown a straight red card. Jean-Baptiste Fischer did well to nick the ball away from Wraight but that didn't seem to bother the Hornchurch man who recklessly hacked down Fischer. The referee had no choice but to brandish the red card and Fischer was lucky that his injury wasn't serious.
From then on it was going to be a uphill battle for the Urchins and it proved to be almost instantly. The resulting free-kick from the red card was floated into the box and after failing to clear the lines, Klaidi Lolos steered home to level the scores.
Half-time: Hornchurch 1-1 Oxford City
The second-half was a much more entertaining affair with chances falling to both sides. Despite being a man short, Hornchurch weren't giving up on their dreams of a cup upset but Sam Higgins fluffed his lines when it mattered most. A shot came crashing off the post and re-bounded into the feet of Higgins who had the whole goal to aim for but could only blaze his shot over the crossbar.
However, just before the hour mark City edged ahead (and in some style). Zac McEachran rolled the ball to Reece Fleet outside the box and the midfielder unleashed a rocket of a shot which arrowed into the top corner of the net, clipping the post on its way in. A super strike worthy of winning any game!
From then on in, it was one way traffic. Four minutes later, Josh Parker cleverly poked the ball past Hornchurch 'keeper Wright and was brought down for a penalty. The striker stepped up himself to take the spot-kick and made no mistake from twelve yards, sending Wright the wrong way.
The win was then a formality for City and they added a fourth goal in injury time. Hornchurch had pushed their squad forward and were caught on the counter, Parker eventually tapping home at the back post after Wright had parried a Lolos shot into the striker's path.
Job done for City who enter the First Round proper for the fourth time in the past five seasons.
Oxford City Starting XI: Dudzinski, Ashby (Potter 45'), Rowan, Coyle, Fleet ©, McEachran (Burley 80'), Lolos, Parker (Muchechetere 90+1), Harrison, Fischer, Carroll
Subs not used: Miccio, Humphrey-Ewers, Carbon