As well as recognising the work of more than 2m people who work and volunteer across the NHS and emergency services, National Emergency Services Day also remembers fallen personnel.
After leading a minute's silence, SKDC Chairman Cllr Breda-Rae Griffin paid tribute to the commitment and courage of emergency services staff, especially during the pandemic.
She said: "The men and women of our emergency services demonstrate incredible courage and professionalism every single day".
"Time and time again, they are there for us when we need them most. As a country, we are indebted to them for their extraordinary commitment to the public.
"This flag raising is our opportunity to honour the work they do and say a heartfelt thank you.
"It is especially important that we acknowledge and commemorate the Emergency Services and the NHS for the professionalism and care they have provided since the COVID-19 pandemic entered this Country."
A prayer of thanksgiving was read by Fr Stuart Cradduck, of St Wulfram's Church, before the flag was raised in front of assembled guests, who included representatives of SKDC's Cabinet and council, its staff and the fire/rescue service, police, ambulance service, Lives emergency responders doctors and the Notts and Lincs Air Ambulance Service.
The annual 999 Day promotes volunteering in the emergency services, educates the public about using the services responsibly, teaches life-saving skills and promotes their work.
More information about 999 Day can be found at www.999day.org.uk