The man, identified as Javed Inamdar, claimed during the trial that he had mistaken the child for his wife while he was asleep when the incident occurred on December 14, 2024, GB News reported.
The court heard that the girl awoke around midnight and shouted at him to stop, before alerting cabin crew.
Inamdar denied the allegations, but a jury at Isleworth Crown Court found him guilty of assaulting a girl under the age of 13 by touching.
In a separate case earlier this year in the United States, 36-year-old Bhaveshkumar Dahyabhai Shukla, an Indian-origin man, was accused of sexually assaulting a fellow passenger on a domestic flight, according to officials.