The 26-year-old joins the Gulls on a three-year deal after a fee of £17,500 was agreed with their Blue Square Premier rivals.
Buckle left the Grecians in June to take up the vacant manager's post at Torquay and has returned to his former club to snap up the former Plymouth Argyle trainee.
"I am delighted to have Lee at the club," Buckle told the club's official website.
"He is a proven goalscorer and will be a big hit with the supporters. Lee was always in my thoughts and this is a major signing for the club.
"I would like to thank Exeter City Football Club for their helpful manner in the proceedings."
Source: http://www.confguide.com/newsArticle.do?id=6690