Newcastle upon Tyne Hospitals foundation trust had been under-paying its skilled electricians, plumbers and technicians by nearly£3,000 a year, an employment tribunal ruled.
The money, known as a recruitment and retention premia (RRP), takes the wages of NHS maintenance and craft workers roughly up to levels found in the private sector.
The pay boost, negotiated as part of Agenda for Change, is used as a way of keeping skilled workers in the health service.
But when the Newcastle trust refused to hand over the full amount, members of trade union Unite - a merger of Amicus and the T&G - threatened industrial action.
The trust agreed to pay up in the short term but took its case to a tribunal. While celebrating the victory, Unite said it was important for other NHS trusts to take stock of the decision.
Unite industrial relations spokesman Barrie Brown said: 'This should never have happened because NHS Employers had already obtained a legal opinion 15 months ago.'
There are around 10,000 workers in the NHS to whom this ruling will apply, although many trusts are already paying the RRP to maintenance and craft workers, he added.
The final judgement of the tribunal decision notes that other professional groups entitled to RRP include dental nurses, qualified midwives, pharmacists and biomedical scientists.