The 53-year-old man had been facilitating an excursion with Year 11 students and staff from Perth's Newman College at Brides Cave in Boranup, near Margaret River.
Police say a number of the group had already abseiled to the bottom of the cave area on Thursday afternoon when the instructor fell.
First aid was provided to the man until a rescue helicopter paramedic was lowered into the cave and took over.
"Tragically, the man became unresponsive and was unable to be revived. He died at the scene," WA Police said in a statement.
The man's colleagues and emergency service volunteers assisted with the recovery of the instructor, students and teachers from the bottom of the cave.
Police have notified WorkSafe of the incident and will prepare a report for the coroner.
Newman College acting principal Lucie McCrory said the students had been taking part in an outdoor education camp.
She extended her condolences to the loved ones of the instructor on behalf of the school.
"The college has deployed all necessary resources to support the wellbeing and pastoral care of students and staff who have been impacted by this tragic incident. They arrived home late last night," she said in a statement on Friday.
"Police have praised the conduct of our staff and students and their response to the emergency services.
"The college will provide such assistance as is necessary to the relevant authorities as they investigate this incident."
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