The extension will use part of the existing London Fenchurch Street - Tilbury line east of Barking, diverging onto a new 1.5km electrified branch at Renwick Road to reach the two-platform Riverside terminus. Barking Riverside is the largest brownfield housing development in east London, with planning permission for 10,800 homes as well as healthcare, retail, and leisure facilities.

The £263m extension is fully funded and the developers of the site, Barking Riverside Limited, will provide £172m towards the project with the remainder coming from TfL.

Construction is expected to begin in late 2017 and the project is due to be completed in 2021, when London Overground's Gospel Oak - Barking services will be extended to Barking Riverside. Electrification of the Gospel Oak - Barking line is due to be completed in 2017 and a new fleet of Bombardier EMUs will enter service on the route from 2018.