Carried out by Passenger Focus, the National Passenger Survey reveals a 92 percent overall approval rating for the Overground service.
The service is routinely scored highly by Network Rail and in 2011 was named as the top performing train operator in the UK for trains arriving on time.
In November 2007 Transport for London took over the Silverlink rail service, rebranding it as the London Overground and promising to improve standards.
A major investment programme included the deep cleaning of all stations, introducing staffing at all stations and the purchase of 65 new, air-conditioned, trains.
In 2010 TfL completed the East London Line extension linking Highbury & Islington in north London with West Croydon in the south.
A second extension, due to enter service in December, will link Clapham Junction to Dalston Junction.
Welcoming the survey’s findings, Mayor of London Boris Johnson said: ‘Passengers have spoken and these results show that our investment in the London Overground network is paying off. We are running more trains, carrying greater numbers of passengers and providing a more reliable service.’
Mike Brown, Transport for London’s Managing Director of London Rail and London Underground, said: “These high rates of passenger satisfaction are due to consistent, punctual operational performance with frequencies of at least 4 trains per hour across almost all the network.
“Where passengers have asked for more trains per hour, we have, where possible, provided that – the enhancement of the Richmond and Clapham to Stratford services being a case in point. ”Passengers are also showing their approval of our new, air-conditioned trains which have a more spacious layout, are fully accessible and easy to board and exit.”