The decision by Roger Elkins, cabinet member for highways & infrastructure, is expected to come into force in October.
It will affect around 2,000 older people while saving the council £50,000 per year.
Like all authorities, West Sussex has a statutory duty to administer the English National Concessionary Travel Scheme (ENCTS), providing free off-peak bus travel for eligible older and disabled people.
There is no such legal duty to provide the railcard scheme.
A council spokesman said all railcard holders would be able to use their cards until the expiry date and would then be given a free bus pass.
They could also buy a replacement Senior Person’s Rail Card from National Rail for £30 for one year or £70 for three years.
The results of a four-week consultation held throughout November attracted 783 responses; 375 of the whom were current rail card holders.
Two thirds said they slightly or strongly disagreed with the idea of dropping the card, while only 20 per cent slightly or strongly agreed it should be withdrawn.
Councillors have until Friday June 19 to ‘call in’ the decision for further debate.
If that doesn’t happen, it will come into force on Monday June 22.
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