The incident happened on the Delhi-San Francisco flight, one of the longest in the world, following which Air India carried out fumigation of the aircraft.
An Air India official said a rat was spotted when the plane had just started taxiing early Sunday morning and subsequently, the take-off was aborted.
The flight was almost full with 173 passengers in economy class and 34 in business class.
After taking the aircraft to the parking bay, it was fumigated and this exercise took about six hours, an Air India spokesperson said.
Adding to the woes, the permitted duty hours of crew expired during the fumigation time and the airline had to bring in a new set of crew. This process took more than three hours and finally the flight took off after a delay of over nine hours, the spokesperson said.
As per aviation regulator DGCA's rules, crew members, that includes pilots, are not allowed to be on duty continuously beyond a stipulated number of hours.
Earlier also, there have been instances of Air India flights getting delayed due to rat menace, among other issues.