The plaque has been placed in the Catherine Cookson Garden at South Tyneside District Hospital.
It was officially unveiled by the Mayor and Mayoress of South Tyneside, Coun Alan Smith and his wife Coun Moira Smith.
The family of Gillian Lyon, were also at the ceremony, which took place following a service and the lighting of candles.
The 42-year-old lost her fight for life after suffering a bleed on the brain in 2012.
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After her death, her son Andrew and mum Sandra Burn made the decision to honour her wishes and allowed her kidney to be donated to help someone else.
Mrs Burn, from South Shields said: “It is marvellous that there is now a memorial, and the service and the unveiling were very emotional.
“We feel Gillian’s loss all day, every day. Now we just want more people to sign up to the donor register.”
Coun Smith, who unveiled the memorial, said: “It is wonderful for our local community to have this focal point to remember and honour all those people who have done something truly amazing, and I’d like to thank South Tyneside NHS Foundation Trust and NHS Blood and Transplant for providing this memorial.”
South Tyneside NHS Foundation Trust’s chief executive Ken Bremner said: “It is important to publicly recognise individual organ donors and their families for their contribution to saving, or helping to change, the lives of others.
“That is why I am delighted that we now have our own memorial acknowledging and celebrating the contribution of our local donors, whose families should all feel very proud.”
Dr Sanjay Deshpande, the trust’s clinical lead for organ donation, stressed the importance of people joining the NHS Organ Donor Register.
To join the NHS Organ Donor Register, call 0300 123 2323 or go to www.organdonation.nhs.uk.