Southern Railway is to cut 341 trains a day in a revised timetable, the company has announced.
The temporary weekday timetable will start next Monday following weeks of delays and cancellations due to industrial action and staff shortages.
Southern said the aim was to reduce the impact on passengers and staff of "unpredictable and late notice" cancellations caused by "unprecedented" levels of train crew sickness and unwillingness among others to work overtime.
The operator said it was also taking action to "encourage staff back to work" and was working with the Government to introduce more generous passenger compensation.
Southern has been embroiled in a bitter row with the Rail, Maritime and Transport (RMT) union over plans to change the role of conductors, which has led to a series of strikes.
Southern's passenger services director Alex Foulds said: "We are introducing this temporary weekday revised timetable with reluctance but it is the best thing we can do for our passengers who have been suffering daily cancellations ever since this dispute with the RMT began, and for which we are sincerely sorry.
"It should give the majority of our passengers a better, more consistent service that they can plan around.
"Whilst our first priority is our passengers, we also understand that this has been a difficult time for our staff. Conductors already know that their jobs are guaranteed, that there will be no reduction in salary and that the independent rail safety body has confirmed our plans are safe.
"Now, after listening to our staff, we have also decided to restore leisure travel benefits. All of this, we believe, should help our staff feel able to return to work and so reduce the issues causing the current high level of train cancellations."
Changes include the suspension of Southern's West London Line services between Milton Keynes and Clapham Junction, reductions in service on the Coastway routes, buses replacing most trains between Seaford and Lewes, and a reduced off-peak service between Tonbridge and Redhill where passengers for Victoria will need to change trains.
Mr Foulds said: "Once again, we urge RMT officials to relax their unbending attitude to our plans and to step over the line in the sand they have drawn opposing any extension of driver-only train operation."
Southern said the number of trains being cancelled is broadly similar to those being cancelled at the moment.