The Department for Transport has approved a £10m grant to go towards the project while Network Rail and Northamptonshire County Council are stumping up the other £10m.
The redevelopment, designed by BDP, is the first step in a substantial regeneration planned for the town by West Northamptonshire Development Corporation.
Work includes a new station building, multi-storey car park, footbridge and platform canopies. The proposed materials combine solid concrete mass with timber structures.
Transport secretary Justine Greening said: “Northampton deserves a station that will be a brand new ‘Gateway’ to the town and stimulate the redevelopment of the station area. But more importantly it will give a boost to the Waterside Enterprise Zone and its ambitious plans to unlock the town are potential and encourage more businesses into the area.”