The result was 'Side's first win at home this season and a much-needed one, as Michael Walter's men moved into the quarter-finals, of the competition held in the honour of the late Peter Butcher.
Ian Read's Hullbride Reserves took the lead on 18 minutes through Perry Dunn.
'Side to their credit equalised on 42 minutes when full-back Derek O'Halem, on his home debut, scored. This ensured the teams went into the break level.
After the break 'Side came out of the blocks brilliantly and took the lead on 48 minutes. Harry Daly, also on his home-debut, on-loan from Romford, finishing to put the hosts ahead.
Hullbridge though levelled the scores on 70 minutes through Arnold Achampong. Despite both side's efforts, neither team could force a winnner before the end of 90 minutes and the game went to penalties.
In a penalty-shootout of high-quality, 'Side went first with the first 17 penalties being scored. Hullbridge's ninth attempt was skied high over the bar as the Sky Blues triumphed on penalties to move through to the quarter-finals. 'Side's Reserves are also through to that stage also after they defeated Sawbridgeworth Town Reserves 5-0 earlier that afternoon.
'Side are next in action on Monday night at home to Takeley, where they will be looking to secure a vital first home league win of the season. Kick-off at Cricklefields for that match is at 7:45pm.
'Side: Mikel Breckenridge, Akwasi Marfo, Toby Barlow, Connor Tyrrell, Harry Matthews, Derek O'Halem, Raphael Duyile, Harry Daly, Peter Oyetunji, Jake Kenneally (Sopuia Ubah), Mattheus Santos