Corey Smith, 19, repeatedly threatened to stab commuters on the Central line in a three-week crime wave in December.
He was arrested at Northolt station in January after British Transport Police identified him from information by a victim who was mugged only hours earlier.
Smith was found to be carrying a lock-knife and £20 notes he had stolen from the Tube passenger.
More victims picked him out of identity parades and police were able to produce CCTV evidence showing him at the crime scenes.
Smith, of Harlesden, was jailed for three years and eight months after pleading guilty at Southwark crown court to five counts of robbery, one of attempted robbery and two of possessing an offensive weapon.
Outside court BTP Det Sgt Terry Botten said: “While violent crime on the Tube is rare, these robberies were very frightening ordeals for the victims.”
Howard Collins, chief operating officer of London Underground, said: “We are glad our CCTV has helped to bring Smith to justice.”