Staff working for South Tyneside and Sunderland NHS Foundation Trust voted in July for strike action in a dispute over fair wages.
The South Tyneside and Sunderland health workers had also campaigned to be given fair back pay for the work they had already undertaken.
Healthcare assistants have been paid at band 2 of the NHS Agenda for Change pay scale, despite increasingly carrying out clinical tasks that should be paid at the higher band 3 rate.
Unison Northern regional secretary Clare Williams said: ‘It's great to see that strikes have been avoided after staff won a hard-fought campaign. These healthcare assistants have been working above their pay band for many years.
‘It should never have come to a threat of strike action, but it's good the trust returned to negotiations and agreed the back pay staff deserved.'
A spokesperson for South Tyneside and Sunderland NHS Foundation Trust added: ‘Our clinical support workers and healthcare assistants are a highly valued and vital part of our workforce.
‘We worked hard during our discussions with the union to resolve this as swiftly as we could and pleased this deal has been agreed.'
Healthcare assistants employed by the North Tees and Hartlepool NHS Foundation Trust and South Tees Hospitals NHS Foundation Trust won a pay rise in July with back pay to 2019, following 14 days of strike action.