The future Socceroo has penned a one-year loan deal with the German second tier club, as he aims to continue his development after 11 appearances in his first season in Europe
Both clubs announced the deal on Tuesday evening, with the 21-year-old striker/winger hoping the loan stint will bring him game-time to aid his development.
"At FSV Frankfurt I would like to take the next step in my development," Leckie told the FSV website.
"Here I would like to earn playing time and play with the club in a successful season."
Leckie joined Monchengladbach in March 2011 from Adelaide United, before making 11 appearances off the bench during the 2011-12 campaign.
Gladbach sporting director Max Eberl said the club remains convinced of Leckie's talent but wanted him to gain experience at FSV.