Banksy also left a note for all workers, which read: "Thanks for all you're doing. I hope this brightens the place up a bit, even if it's only black and white."
He also described the efforts of health workers across the world as a "game changer".
The painting will remain at Southampton General Hospital for a few months before going to auction to raise money for the NHS.
Paula Head, CEO of the University Hospital Southampton NHS Foundation Trust said: "Our hospital family has been directly impacted with the tragic loss of much loved and respected members of staff and friends.
"The fact that Banksy has chosen us to recognise the outstanding contribution everyone in and with the NHS is making, in unprecedented times, is a huge honour."
She added: "It will be really valued by everyone in the hospital, as people get a moment in their busy lives to pause, reflect and appreciate this piece of art. It will no doubt also be a massive boost to morale for everyone who works and is cared for at our hospital."
Nurses and fans of Banksy to praise both the artist and fellow healthcare workers for their Covid-19 efforts.
"Omg such a lovely image after a weary day of nursing. Thank you for bringing a smile to my face," one nurse said.
Another added: "This made us fill up but in a good way banksy. Our eldest is a nurse on ICU thank you."
A third said: "The paradigm has shifted indeed, Banksy. Heroes exist in fiction and in reality and our society has now a new appreciation for them."
