Teenager Jayden Stockley struck twice as Woking inflicted a blow to Wrexham's promotion hopes.
The 19-year-old took advantage of the visitors' flat display to give the hosts only a second win in their last 11 games.
Wrexham remain third in the table, but are now 10 points behind second-placed Mansfield.
Woking climbed two places to 10th after Stockley found the back of the net twice in 10 second-half minutes.
VIEWS FROM THE DRESSING ROOM
Wrexham player-manager Andy Morrell told BBC Radio Wales:
"We didn't take our chances. We and created four or five, really.
"[They] were good opportunities and they didn't fall for us and we didn't make them count.
"And then we let them get their tails up and I think in the second half you could see the effects of a busy week because the lads looked out on their legs and it's the worst 45 [minutes] of football we've played, so on to the next."
Woking manager Garry Hill told BBC Surrey:
"We rode our luck today but we had a lot of belief that we could win the game in the second half and I think, in the end, we deserved to win the game.
"There was nothing wrong with the pitch today. There was more desire from a team that wanted to win it more. We're a club trying to find stability back in the league after four years.
"We grew in confidence and had a great deal of work-rate. When you see the desire and work ethic of our team out there today, nobody could turn round and say who was a part-time club and a full-time club."