The former Sunderland man agreed a short-term contract with Augsburg in January, having previously spent time on loan at the Bundesliga outfit, before being swiftly snapped up by Dortmund for the beginning of the 2014-15 campaign.
However, Ji has failed to make a single outing for Dortmund since arriving at Signal Iduna Park, and will now return to Augsburg on a three-and-a-half-year deal for an undisclosed fee.
"I am pleased to now be able to wear the FCA jersey again," he said. "I want to find my form as soon as possible and help the team to achieve its goals."
Augsburg CEO Stefan Reuter added: "When the opportunity arose for Ji Dong-won to join us we jumped at the chance, because we get additional quality in the squad.
"We know him, he knows us and we are sure that he can build on the services he has shown here in this environment in the past."
Ji's only league goal in 12 appearances for Augsburg last term came against Dortmund, after he had agreed to join Jurgen Klopp's side in the close season.
