Jatinder Singh, 35, aka Vicky Singh Sangha took advantage of the busy crush of passengers to touch the victim.
He pleaded guilty to sexually assaulting the woman, aged in her thirties, on the westbound Central Line London Underground train on Wednesday, October 2, 2024.
Inner London Crown Court heard Singh boarded just after 8.20am at Liverpool Street Station.
Once on the busy service, he sexually assaulted the woman.
Sangha exploited the extremely busy carriage and tight space to conceal what he was doing to the woman from other commuters.
The victim bravely texted BTP on 61016, and only days later an officer familiar with the incident recognised Sangha outside King's Cross Station and arrested him.
Investigating officer Detective Constable Steven Ridpath-Mitchell said: "Sangha's opportunistic behaviour was totally unacceptable.
The victim was trying to go about her daily life on her way to work and should not have been subjected to his abhorrent and despicable actions.
"It is down to the bravery of the victim and the keen observation of an officer that we have been able to arrest, charge and sentence Sangha and see him held accountable.
"The victim has bravely supported the investigation throughout, ensuring that Sangha will now have plenty of time to think about his actions while in prison and feel the consequences for years to come.
Singh must also sign the sex offenders register for ten years and pay a £187 surcharge.
