Commuters will not face a fare hike next year when a train line through Waltham Forest becomes a part of the Overground network.
It was feared travellers could be hit with higher costs on the Chingford to Liverpool Street line after Transport for London (TfL) took over the running of services.
The cost of a standard adult annual season ticket from zones one to five is £1,560 under current operator Greater Anglia.
But TfL currently charges £2,136 for an equivalent ticket on the Overground and Tube.
TfL has not ruled out changes to the fare structure in the future, but said the season ticket price would not increase next year.
TfL’s director of rail, Jonathon Fox, said: "We are working with the Department for Transport and Abellio Great Anglia on the transfer of some West Anglia services to the Mayor’s control in 2015.
"Transferring services will adopt the same fares and concessions structure as on all the Mayor’s London Rail services, so fares to London will fall by up to a third using the Oyster.
"There are no plans to withdraw point-to-point season tickets when the routes to and from Liverpool Street transfer.”
Councillors and Chingford MP Iain Duncan Smith raised concerns with TfL over a possible price hike last month.
Cllr Sheree Rackman, who represents Hale End and Highams Park, said: "As soon as we heard that our constituents and service users could be in with a fair increase, we were on the case, but we have now been assured that this will not be the case.
"We are delighted and hope that this will put Highams Park on the map and hope that being a part of the TfL network should hopefully bring benefits to our area."
Mr Duncan Smith said: "Bringing the line in to London Overground will bring many benefits, but these particular passengers were very concerned by the threat to their season ticket prices.
"I am really pleased that local Conservatives were able to pressure TfL into guaranteeing that they won’t be penalised."