Kim - the current world champion and a silver medallist to Bischof at Beijing 2008 - caught his opponent twice early on with leg sweep throws, which scored him two Yuko.
Canadian Antoine Valois-Fortier - who had earlier knocked out European champion Elnur Mammadli of Azerbaijan - came through the repechage to claim bronze with a battling Yuko win over American Travis Stevens, drained after his epic semi-final loss to Bischof.
Defeated semi-finalist Ivan Nifontov added to Russia's judo medal haul with bronze after he beat Takahiro Nakai of Japan.
Top seeded Brazilian Leandro Guilheiro was knocked out in the quarter-finals by Stevens, and then lost in repechage to Nakai.
I could not use my left shoulder, but nevertheless I was able to make it to the gold medal. I think it was thanks to GodKim Jae-bum
'Four years ago I did my best even though I ended up winning the silver medal. From then on, for four years I did my best. As a result I was able to gain the gold,' Kim said.
'If I was too nervous or if I had not trained hard and prepared enough, I might have lost to him.'
Kim includes prayer in his pre-match warm-up, and said: 'I had injuries to my shoulder, ribs, knee, fingers and everywhere.
'I could not use my left shoulder, but nevertheless I was able to make it to the gold medal. I think it was thanks to God.'