The town's Chamber of Commerce has announced that the future of the service is under severe threat unless more traders can contribute £10 a month to its running costs.
Currently, about 20 businesses are supporting the park and ride but about 40 are needed to make it sustainable, the chamber has said.
The service, which is in its fourth year and has proven popular with visitors to the town, is operated by volunteers and relies on businesses to support the scheme.
Chairman of the Chamber, Steve Robbins, said to the executive committee at a meeting last Tuesday that it no longer had sufficient funding coming in to cover the costs of running the park and ride and it no longer had the resources to continue subsidising it.
He said: "It is extremely disappointing having put so much effort into starting up and improving the service to bring more visitors into the town, that we now find ourselves in this situation."
The Chamber subsidised the service for the first two years before introducing a £2 parking fee to offset costs of using the car park, belonging to Nock Deighton, and the upkeep of the minibus, which travels about 70 miles a day.
Mr Robbins added: "Passengers travel for free on the bus and are even able to send their shopping back to the car park on it where it is looked after for them until they are ready to return from town.
"Many comment on what a wonderful service it is and how they will return to Bridgnorth in the future and use it again.
"That is what we want to hear, but we need all traders who benefit from the increase in shoppers to contribute towards its operation.
"The Chamber is a non-profit organisation so we don't make any money at all from the service and unfortunately we're at the point now where we're seriously having to consider whether we can continue to operate it in the future.
"Members of the chamber are having to give up their time for free on weekends to drive the buses and operate the service but unless more are willing to support it I cannot see how we can continue next year."