Ethan Suglo, from Ghana, was flown to Oxford to be treated for exomphalos.
In 2015 doctors David and Jacquie Williams met Ethan in Ghana and helped raise £39,000 to fly him over for surgery at the John Radcliffe Hospital.
Charles Suglo commended everyone at the hospital for a “marvellous job… [they were] fantastic”, he said.
Exomphalos can prove fatal and doctors in Ghana and Nigeria were unable to help, although it is regularly treated in the UK.
Paediatric surgeon Hugh Grant said helping Ethan had been “very fulfilling” and “very rewarding”.
Mr Suglo said: “I was amazed to see what has happened… each and every day we see much progress about his health.
“Ethan is happy, playing, chatting, eating, drinking, so life is back for him. It was a great relief. We cannot express the joy.
“I just say ‘wow, I have peace of mind, everything is going to run smoothly in the family.'”
Mr Suglo said he expected Ethan to be observed at the hospital for a few more weeks before they returned to Ghana, where his mother Bless is waiting.
Mr and Mrs Williams, from Stretton-on-Fosse, Warwickshire, met Charles at the radio station where he works while visiting their daughter Laura who was doing voluntary work.
He asked them to look at his son, who he said had “a swollen tummy”.
“I thought I would be examining a normal African child with malnutrition,” Mr Williams said.
“But it was clear he had a major abdominal defect.”
Exomphalos occurs when a child’s abdomen does not develop fully in the womb.
During pregnancy the intestine develops inside the umbilical cord and then usually moves inside the abdomen after about 10 weeks.
In Exomphalos the intestines and sometimes other organs, such as the liver, remain inside the umbilical cord but outside the abdomen.
There is no known cause and about half of all babies with the condition will have problems affecting other organs, particularly the heart, lungs and kidneys.
Surgery is essential and takes place in either one go or over several weeks, depending on its severity.