Tom Shaw's injury-time winner saw Cambridge United leapfrog visitors Woking into 11th in the table.
Kevin Betsy forced a good save from Cambridge's debutant keeper Nick Pope before Shaw drew Seb Brown into action at the other end.
Betsy missed a glorious opportunity and Jayden Stockley thought he deserved a penalty after a challenge by Kevin Roberts in the U's box.
And Shaw poked in Curtis Haynes-Brown's cross on 93 minutes to snatch the win.
VIEW FROM THE DRESSING ROOM
Woking manager Garry Hill told BBC Surrey:
"We probably thought we got the break right at the end when one of their defenders fouled Jayden Stockley and I cannot believe what I've seen.
"Why didn't he book the boy for diving? it was a very bad decision from the referee and he didn't have a lot to do today.
"But we got punished after that and we should have dealt with it, and I thought we should have got three points today, it hurts."
Cambridge United 30 Pope 02 Roberts Booked 03 Anderson 12 McAuley 22 Wassmer 06 Shaw Booked 11 Dunk (Haynes-Brown - 87' ) 16 Jarvis 08 Reed 17 Hughes (Pugh - 82' ) 19 Blissett Substitutes 24 Ross 26 Brighton 34 Haynes-Brown 18 Berry 15 Pugh Woking 30 Brown 02 Newton (Frith - 66' ) 05 McNerney 08 Parkinson 16 Johnson 26 Nutter 04 Ricketts Booked 11 Betsy 15 Sawyer 09 Bubb (McCallum - 75' ) 25 Stockley Substitutes 37 Little 03 Mike 19 McCallum 22 Frith 17 Francis