The blaze took place at Meden School, on Burns Lane at around 2pm on Friday November 3.
No one was hurt during the incident.
Two breathing apparatus, two hose reel jets and a positive pressure ventilation fan were used to put out the blaze.
Warsop firefighters were joined by a crew from Shirebrook Fire Station.
Both fire crews left the school at 3.48pm.
Students and teachers returned to the school as usual on Monday November 6.
A spokesman for the school said: “At around 2.10pm this afternoon a small fire broke out in a toilet block at Meden School.
“This triggered the alarm and the evacuation of the school.
“The fire brigade were called and they arrived very quickly and brought the fire under control.
“The conduct of the students during the evacuation was exemplary and I am hugely proud of their maturity and the care they took of one another during this event. “The fire itself was very small and at no time were staff or students at risk.
“However, at times such as these we have to take advice from the fire service and we were instructed not to allow students to enter the building or leave the site until they had concluded their operations.
“We look forward to welcoming the children back at school on Monday as normal.”
The cause of the fire is still unknown.