The deal will allow Associated Newspapers to replace copies of its morning freesheet Metro with copies of its afternoon title, London Lite, in Metro bins across the DLR system, letting the publisher reach the estimated 60m passengers that use the system each year.
Don Gray, circulation director of Metro and London Lite, said: "We are obviously delighted with this new deal with Serco Docklands, which will allow us to reach many more people with the London Lite product."
London Lite's arch rival thelondonpaper, published by News International, will still be allowed distribute copies outside DLR stations, but not have access to passengers inside the stations.
Thelondonpaper was awarded a contract by Canary Wharf early last month to exclusively distribute copies of the paper to the 90,000 people who are employed at the site.
The two freesheets have been involved in a battle in recent weeks about allegations of paper dumping. Associated Newspapers produced video evidence of three thelondonpaper distributors dumping thousands of spare copies of the paper in bins in the inner city.
This led News International to launch an ad campaign in trade titles attacking Associated's Evening Standard, stating that the publisher had launched a "dirty tricks campaign" to destroy competition.
News International subsequently also released photos of dumped copies of London Lite.
The Audit Bureau of Circulations then became involved, releasing a statement saying it takes any transgression of reporting standards very seriously and therefore it would be investigating the claims.
Media buyers have warned that the smear campaign by both sides will create a backlash from media agencies because it gives them ammunition to reject increases in ad rates, which the papers are reported to be requesting.
London Lite and thelondonpaper are currently in talks with Westminster City Council to reach an agreement for contribution to its £500,000 recycling plan. The council has warned if an agreement is not reached then they will "severely curtail" distribution of all free literature in the borough, but it is understood talks have so far been productive.