Five-year-old Corey Edwards, from Teignmouth, Devon, who had a congenital heart defect, was being treated at the Bristol Royal Hospital for Children.
Jemma and Craig Edwards decided on the bedside wedding when they were told Corey could die in hospital.
Corey died on Thursday evening, five days after his parents got married.
Mr Edwards said it was "a day we will never forget".
Corey, who was diagnosed with a complex congenital heart defect when he was seven months old, was on the paediatric intensive care unit after being admitted in January.
His parents organised Saturday's wedding in 48 hours, after being told their son did not have much longer to live. They also had to get special permission from the Archbishop of Canterbury.
Mr Edwards said: "He's [Corey] asked quite a few times why we are not married, so we thought we would make it a special day and cheer him up a bit."
The couple said they "rushed into town" to buy wedding clothes and "made do with their engagement rings".
Hospital staff helped, with one nurse doing the bride's hair and another making the wedding cake.
Craig Edwards said: "Instead of being at his bedside crying the whole time at least on that one day we had a real special day. We know he was happy that day."
Hospital chaplain the Reverend Stephen Oram said: "It was fulfilling the wish of a dying child.
"It was also emotional because we knew the outcome for poor Corey isn't going to be a good outcome and everyone was just aware of the specialness of the day for Mr and Mrs Edwards and Corey."
A terminally ill boy had his wish to see his parents marry granted when they had their wedding at his hospital bedside days before he died.