Lancashire County Council will provide £50,000 towards the Changing Places facility as part of its programme to improve accessibility at key sites.
Changing Places are larger than standard accessible toilets and include equipment such as a changing bench, shower and hoist to support people with a range of disabilities.
This facility will be installed and operated by Avanti West Coast, who manage the station and are contributing £112,000 towards the project.
The county council's contribution was approved by its Cabinet on Thursday 5 May.
County Councillor Alan Vincent, deputy leader and cabinet member for resources, HR and property, said: "I'm pleased we're providing funding towards this much-needed facility working in partnership with Avanti West Coast.
"Standard accessible toilets meet the needs of some people with disabilities, but not everyone.
"There are over 230,000 people in the United Kingdom who need assistance to use the toilet or change continence pads, including people with profound and multiple learning disabilities, spinal injuries and people who have suffered strokes.
"Many people find themselves in the unacceptable and undignified position of having to wait until they get home or having to change continence pads on public toilet floors.
"However, Changing Places toilets have the right equipment to ensure people who need assistance, and their carers have superb facilities in easily accessible locations.
"Lancaster Railway Station is a key transport hub with an annual footfall of more than 2 million, so it's vital that this facility is being installed here."
Matthew Worman, regional growth manager at Avanti West Coast, said: “We want the railway to be accessible for all and are pleased to be working with the county council to provide a facility that meets the needs of people with disabilities.
“This investment is part of Avanti West Coast’s commitment to enable independent travel for everyone. Once complete, we’re sure this facility will improve the overall experience for disabled customers when travelling to and from Lancaster.”
The county council's Lancaster Railway Station grant is a key part of its Changing Places Programme.