West Yorkshire fire crews battled the blaze at White Wells above the town.
Six appliances and two wildfire units were at the scene.
Photographs on social media showed flames ravaging the moorland on one of the warmest days of the year so far.
The weather led Facebook group Ilkley Chat to post a warning yesterday morning about the dry conditions.
The spring dry spell has been blamed for several wildfires on moorland in the South Pennines since mid-April, and walkers are being warned to take extra care.
The area’s Fire Operations Group said more fires could start. The group’s chairman, Danny Jackson, said wildfires were the biggest single threat to the area’s rare animal habitats.