The landing was made as a “precaution” after a passenger alerted crew members to the device that was in someone's luggage.
Flight EZY2618 took off from Hurghada in Egypt on Tuesday evening and was due to land at Luton Airport in the early hours of Wednesday.
But the flight was diverted to Rome Fiumicino and rescheduled to operate the following morning.
A spokesperson told Sky News: “The captain took the decision to divert as a precaution in line with safety regulations.
“The aircraft landed safely and passengers disembarked routinely and we provided hotel accommodation and meals where available.
“As some customers remained in the airport, they were provided with refreshments.
“The safety of its passengers and crew is easyJet's highest priority and easyJet operates its fleet of aircraft in strict compliance with all manufacturers' guidelines.
“We would like to apologise to all passengers for any inconvenience caused by the diversion and subsequent delay.”