Arriva Rail London has won a £1.5bn contract to operate the London Overground line, Transport for London (TfL) has announced.
The firm, which is owned by German rail group Deutsche Bahn, will operate the line for the next seven-and-a-half years, with an option to extend the contract for a further two years.
Arriva will take over operation of the rail network in November.
It has promised to modernise stations and provide more frequent services.
Arriva beat bids from five other competitors, including Go-Ahead Group and MTR Corporation, with which Arriva currently runs the line as a joint venture.
MTR and Arriva decided to submit competing bids when the franchise came up for renewal.
Go-Ahead said it was disappointed not to have been awarded the contract and would seek feedback from TfL.
New trains will also be introduced in 2018 on routes out of Liverpool Street and on the Gospel Oak to Barking line.
Some routes will see extended operating hours, while Arriva plans new services on some routes on Boxing Day.
TFL said that London Overground had seen passenger numbers rise by 400% since 2007 and that the network had become one of the most reliable in the UK.
Arriva will be expected to deliver sustained improvements in performance levels. It will also have to meet tough performance targets. If those are missed, it will face new financial penalties, even for incidents caused by Network Rail, train and freight operators.