McKillop said that the 1500m event, which was not included in the Paralympics schedule in Beijing, is his best discipline and was delighted to win gold.
"It was unreal to come back and try and win the 1500," he said. "It wasn't in Beijing to get the chance to run it here was great as it's my event.
"It's very hard [to come back after the 800] but I've put in the effort for months and years. Getting the chance to top the field is unbelievable."
McKillop's mum presented her son with his gold medal at the ceremony.