Dan Smith and Dan Gifford both got braces with Tom Holland getting a late goal after coming on as a substitute.
Early on Calvin Davies did very well to get the ball forward to Lucas Pattenden but his instant cross inside the first few moments sailed out of touch.
Tommy-Lee Higgs latched onto the quick freekick to find Dan Smith on the overlap and on the turn his strike flew over the crossbar from the edge of the box.
A corner on 9 minutes found the head of Kieran Douglas who headed it only as far as Ashley Dugdale who diverted it back at goal but wide of the left post.
Matt Burgess did well to set up the returning Joe Rabbetts on the turn. Rabbetts made a little run before shooting high and wide.
Bognor took the lead though on 20 minutes. Pattenden sped through after Bognor won possession. He ran through and cut the ball back to Smith who fired it into an empty net with the goalkeeper stranded.
Pattenden then fired on goal but he got his boot under it as it flew over the goal. In response down the other end it was Luke Roberts who forced Ryan Hall into a parried save.
Sam Henderson received a swift cross from the left and on the back post forced a brave stop by Hall on 29 minutes.
Then Davies did well to pick out Pattenden on the right. He did well to pass square to Tommy-Lee Higgs who had a quick shot only just bobble wide of the left post on 31 minutes.
Bognor netted their second of the evening on 33 minutes. Isaac Olaniyan did very well to win the ball on the left before beating his man and squaring it to Smith who diverted it in. The ball flew low into the net despite Smith finding a pocket of space in the crowded penalty area.
On 39 minutes Josh Neathey went into the book for a late challenge from behind on Olaniyan, who was clearly fouled.
Olaniyan was deemed to have fouled J Neathey but the ball in by the winger was poor and bounced out of for a goal kick.
A swift freekick from the right by J Neathey saw him curl it onto the head of Danny Howick in the area and his header had to be steered around the post by Hall.
Then Joe Briffa was fouled near the halfway line by Sam Henderson and he was booked on 49 minutes.
Davies found Pattenden on the right again and he sped inside the area to pass the ball across the goalmouth but Higgs failed to get good contact on the ball.
Pattenden cut the ball back to Dan Gifford who swung his boot at the ball and he forced a save from Aaron Jeal on 54 minutes.
J Neathey stole possession and went through on goal but his shot was hit straight at Hall.
In response, Bognor’s Davies did well to find Gifford on the turn and he did well to get a shot away but again Jeal pushed it away.
Matt Burgess picked out Spencer Spurway in the area. His glancing header was somehow diverted off the line by YMCA on 60 minutes.
Olaniyan was fouled again on 60 minutes as Jamie Rice went into the book.
Then Olaniyan set up Gifford on the back post. Gifford diverted it over the bar unmarked.
Gifford was deemed to have been fouled on 67 minutes. Gifford stepped up to take it and he smacked it high into the left side of the net, sending Jeal diving in the wrong direction.
The assistant manager Dean Carden was shown a yellow card on 73 minutes complaining about an offside decision.
Then Tom Holland passed square to Higgs who picked out Gifford. The striker played it back in a one-two move but Higgs’s first time effort was stopped by the goalkeeper.
Bognor extended their lead on 82 minutes with a flowing move. Burgess picked out Tom Holland on the right who unselfishly squared it to Gifford to fire home.
Danny Howick was heroic at the back to scoop the ball off the line. This occurring as Spurway kicked the ball off Hall and the ball almost rolled into Bognor’s net on 87 minutes.
Bognor didn’t stop there though with the goals. Nice build up by Olaniyan and Gifford led to Tom Holland making a short run before firing the ball into the net off a defender deep into stoppage time.
Rocks now take on Whitehawk in the next round with the date to be announced. Rocks return to league action next on Saturday 11 November against Haringey Borough with kick off at 3pm.
Rocks: Hall, Davies (c), Rabbetts, Briffa (Vince 68), Douglas (Howick 45), Spurway, Pattenden (Holland 76), Burgess, Smith (Gifford 45), Higgs (Ellis 80), Olaniyan