Ormonde-Ottewill, 19, was a regular in Arsenal’s Under-21 side last season and has represented England at youth levels.
He told Swindon’s official website: “It’s a great club.
“They play young players and it’s a good opportunity for me to get first-team minutes.
“I’m a left wing-back, I like to get forward, but obviously still do my defensive duties. It fits the way Swindon play and that’s a good reason why I moved.”