Over 200 union members at Harrogate District NHS Foundation Trust have voted overwhelmingly against plans by the Trust to set up a private company.
The Trust announced plans to set up a wholly-owned subsidiary to manage its estates and facilities in November last year.
But the proposed new company, Harrogate Healthcare Facilities Management Ltd, would see the transfer of over 300 NHS staff members and has been met with opposition.
After holding a ballot to gauge members' views in January, Unison have announced that 97 per cent of the 246 voters are against the Trust's proposals.
Sarah Keig, North Yorkshire Area Organiser for UNISON said: "89 percent of our members turned out to vote and from that 97 per cent voted in favour of industrial action up to and including strike action.
"We know staff are extremely angry by the proposal. They do not want to be transferred across to a private company where their contract’s terms and conditions could be affected.
"This will create a two tier workforce and allow for attacks on staff’s terms and conditions."
The union also expressed concerns over the impact on other government-funded services after suggesting that the Trust will make large savings by using the company to avoid paying VAT.
Ms Keig said the results of the ballot were "expected".
She added: "Our members chose to work for the NHS and they have voted strongly against having that right taken away from them.”
But the Trust have disputed claims that the plans will "open the backdoor to privatisation".
Robert Harrison, Chief Operating Officer at HDFT, said: “We have engaged very closely with our members of staff affected by the establishment of the new subsidiary company, and their trade union representatives, throughout this process.
"We recognise the trade unions’ right to conduct an indicative ballot of their members as they have now done.
“We recognise that this is a time of change for staff affected, and we are continuing to closely engage and involve them throughout the process.
"Dialogue with union representatives is continuing as we move forward, and this is something we value and consider is important to maintain in the hope that we can reach agreement on a way forward with certain matters.
“We are holding joint staff engagement events with our trade union colleagues for affected staff to attend. These are currently underway.
“As previously explained, on transfer, current staff will retain their NHS terms and conditions, or if they prefer, they can choose to move to new terms and conditions offered by the company.
"The new company will be modernising pay, terms and conditions for new staff, which will ensure that it is competitive in the local employment market.”