Nicky Ajose’s fifth goal of the season saw Crewe gain their third straight win over local rivals Port Vale and move out of the League One relegation zone.
Ajose could have given the visitors an early lead, but his penalty was saved by Chris Neal after he had been brought down in the box by the keeper.
Ajose’s vital strike then came as he poked home a Jamie Ness through ball.
Vale’s Tom Pope saw a late header saved and Chris Lines’ long-range effort hit the bar as Crewe held out.
The win for the Alex is their fourth in their last six league matches and lifts them two points above the drop zone.