McKillop ran a perfect race in his final to retain his title and said after the race he wanted to match Smyth's achievement.
"Whenever you've won it once you want to win it again and I'm so glad I managed to do it," McKillop said. "I ran exactly the same race that I did in New Zealand in 2011 when I ran away from the group.
"I was inspired by Jason. We are roomies and best friends as well. I couldn't have walked in tonight without a gold medal round my neck.
"The atmosphere was about 10 times better than Beijing because my family were here. It was brilliant for them to see me and an honour for me to run in front of my mum."
Ireland have four gold medals so far in the Paralympics.