Conisbrough Castle was lit up in blue lights on Sunday night in the emotional tribute after English Heritage bosses agreed to the special request.
A spokesman said: “We have had many many moving stories attached to requests to change the castle colours.
"Therefore as a mark of deep respect and love for all those poorly children and people who are struggling in our community we have turned the castle blue.”
The historic keep has been lit up on a number of occasions in recent years, largely for Remembrance events and other special occasions.
Last week, bosses said they would consider requests from individuals for special light displays but admitted that it would not be able to comply with all of them and bosses have also ruled out any displays for political purposes.