The League One spell was his first loan experience away from the Blues.
"I really enjoyed it," Rankine told the club's website. "Before I started I just really wanted to go there, play men’s football and get good minutes. But when I look back on it, it exceeded my own expectations. I played plenty of football, I made friends for life and enjoyed every minute.
"Comparing it to playing for the Under-21s, you’re playing so much more football – sometimes two or three games a week. It’s a completely different challenge. And then you have the actual matches where teams play completely differently from anything I had come up against before. It’s just so different.
"The fans were great as well. Exeter is fan-owned so they are really supportive and really invested in the team. I felt that, and the whole team felt that extra boost when we played at home.
"I think I had a good season and it was good to have my first full season in men’s football. I’m excited and ready to go and kick on."