Lee Byer, 44, appeared briefly at Willesden Magistrates Court in north London on Friday.
Wearing a prison-issue grey tracksuit, he spoke only to confirm his name, his date of birth and that he had no fixed address.
He is charged with murdering 87-year-old Mr O’Halloran, as he drove his mobility scooter along Western Avenue in Greenford, next to the busy A40.
Byer is also charged with possession of a knife.
The incident happened at around 4pm on Tuesday.
Thomas O'Halloran
Metropolitan Police
Lee Byer appeared at Willesden Magistrates Court on Friday
Jonathan Brady
After being stabbed in the chest, the pensioner managed to drive his mobility scooter for another 75 metres, until he came across members of the public who tried to help.
Despite the efforts of paramedics and the London Air Ambulance, Mr O’Halloran, originally from County Clare in the west of Ireland, was pronounced dead at the scene.
The pensioner’s family, including a sister, brothers and nieces and nephews, is being supported by specialist officers.
Mr O’Halloran was a well-known face in the Greenford area, and would often busk outside the local Tube station.
The day after his death, police released CCTV images of a man seen running from the area around the time of the stabbing.
Within hours, detectives had a name and address and armed officers raided a property in Southall, west London.
Lee Byer was remanded in custody and will appear at the Central Criminal Court, the Old Bailey, on 23 August.