Paul Clayton scored twice as Alfreton extended Woking's winless run to four league games.
Town took the lead when Clayton headed Josh Law's cross past Woking goalkeeper Aaron Howe.
Woking improved after falling behind and found an equaliser when Brett Williams fired home from 12 yards with his right foot.
Clayton's ninth of the season proved decisive, however, as the striker powered a header home from six yards.
VIEW FROM THE DRESSING ROOM
Woking manager Garry Hill told BBC Surrey:
"We got punished again today. It's the same old habit at the moment of conceding more then scoring and it's very frustrating how we lost that game.
"We concede too many goals and they've had two attacks today and everyone's been given a job to do and they then punish you.
"I can't knock the effort and commitment today but everything isn't going our way and we have to sort it out."