The Cards, well-known for their cup exploits over the years, left it late, but battled back to earn a Second Round replay.
Ryan Tafazolli gave Posh the lead after 24 minutes from close range after Woking `keeper Nathan Baxter was unable to hold a header from their former loanee Jack Marriott.
The home side had a great chance to get back on level terms 5 minutes before half-time when Alex Penny fouled Inih Effiong in the area.
But Posh `keeper Jonathan Bond saved Cez Isaac`s spot-kick.
The home side kept plugging away though and were finally rewarded 6 minutes from the end of normal time when Nathan Ralph`s cross was converted by Joe Ward from just inside the box.
Woking`s league rivals Guiseley AFC, Gateshead and Boreham Wood suffered defeats.
The Lions were beaten 3-0 at Field Mill by League Two Mansfield Town and ended the game with only nine-men.
It took the home side until just after the half-hour mark to break the deadlock, although they had missed several opportunities before Jimmy Spencer headed home Paul Anderson`s cross from close range.
Guiseley `keeper Jonny Maxted kept his side in it but they suffered a massive blow 5 minutes before half-time when they had defender Darren Holden sent-off for a challenge on Spencer deemed reckless.
It got even worse for former Mansfield boss Paul Cox`s side when, 6 minutes into the second period, they went down to nine-men when Chris M`Boungou was dismissed for a second yellow card offence.
Just over a minute later, Spencer added the Stags` second with a neat finish from CJ Hamilton`s cross and he completed his hat-trick and Mansfield`s comfortable passage into the Third Round when he converted a 65th minute penalty after he had been brought down by Danny Lowe.
League Two high-flyers Luton Town showed those in attendance at the International Stadium just why they are favourites for the title as they demolished Gateshead 5-0.
It took 40 minutes for the Hatters to make the breakthrough when a defensive mix-up ended up with Olly Lee firing home from the edge of the area.
The game was held up following the goal, however, due to a serious-looking injury to Heed defender Scott Barrow, who was carried off unconscious after a collision with his own keeper Dan Hanford.
Luton doubled their advantage after 63 minutes when Dan Potts headed in an Andrew Shinnie cross and 5 minutes later, Elliot Lee made it 3-0, thanks to an assist from brother Olly.
The home side`s Danny Johnson and Paddy McLoughlin were unfortunate to see their efforts hit the woodwork and then two goals in stoppage time from Danny Hylton and Luke Berry made the scoreline a little harsh on Gateshead.
Boreham Wood fell to a 3-0 defeat at the Ricoh Arena against former winners Coventry City.
The Sky Blues took a 27th minute lead when Duckens Nazon pounced on a loose ball after Wood `keeper Grant Smith had saved well from Marc McNulty.
Five minutes before the break, City doubled their lead when McNulty lobbed Smith superbly.
Three minutes into the second period, Wood`s cup run was over when Jordan Shipley converted a McNulty cross at the far post.