The route 241 bus route will now link the Royal Wharf development in Silvertown to destinations across London.
Before September 24, the 241 ran between Stratford City bus station and Prince Regent bus station.
It has now been extended southwards to Royal Wharf, via Connaught Bridge and North Woolwich Road, serving three extra stops each way.
The extension provides a direct link between Royal Wharf and Elizabeth line services at Custom House. This means Silvertown residents have access to Canary Wharf and Liverpool Street, as well as west London and Heathrow Airport.
This comes amid controversy over bus cuts proposals and the government's Transport for London (TfL) funding deal.
Geoff Hobbs, TfL's director for public transport planning, said: "This new extension to route 241 will open up a wealth of jobs and opportunities to those moving into the Royal Wharf development.
"But that's not the only benefit of buses serving the neighbourhood - with fewer cars expected thanks to the new transport connections, the area will enjoy less congested, quieter roads and improved air quality."
The 241's new terminus is a walk to Royal Wharf pier, allowing for interchange with Uber Boat by Thames Clippers services to central London.
The extension comes as Bus Users UK marks Catch the Bus month, which celebrates the bus as a sustainable, inclusive and accessible form of transport throughout September.
All buses on route 241 are low-floored vehicles with access ramps.
Claire Walters, chief executive of Bus Users UK, said: "Buses are the lifeblood of London, providing access to education, employment and life's opportunities.
"They also cut congestion and improve air quality, and we would urge people to give the bus a go for this September's Catch the Bus month."
The route has retained its current frequency, with the first buses to depart from Royal Crest Avenue at 4.55am on Monday to Saturday and at 5.57am on Sundays.
The last service from Custom House in the direction of Royal Wharf departs at 1.13am throughout the week.
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