Rail routes will be given a shake-up from December 9 with the new timetable.
The main changes for Bedfordshire commuters will include the 0733 Bedford to Sutton service being diverted to Brighton, calling at London Blackfriars, East Croydon, Gatwick Airport, Three Bridges, Haywards Heath and Brighton.
The 0744 Bedford to Elephant & Castle train will be extended to Sutton via Wimbledon, calling at London Blackfriars, Herne Hill and all stations to Sutton via Wimbledon. This service will no longer call at Elephant & Castle.
The 1740 London St. Pancras International to Three Bridges service will start from Bedford at 1640 and call additionally at Flitwick, Luton, Luton Airport Parkway, Harpenden and St Albans.
On Saturdays, the 1907, 1937, 2007 and 2037 Brighton to Bedford services will call additionally at West Hampstead Thameslink, and the 1754, 1824 and 1854 Bedford to Brighton services will also call additionally at West Hampstead Thameslink.
New timetable books will be delivered to stations early next month.
Neal Lawson, managing director of rail operator First Capital Connect, said: “With every timetable change we aim to make adjustments to give customers a better service.
“The end of sustained closures across central London for Thameslink Programme engineering work has allowed us to deliver these improvements.”