The world champion's total of 700 points during the ranking round at the Sambodromo venue eclipsed the previous record of 699 set by compatriot Im Dong-hyun, which was set in the London Olympics' preliminary four years ago.
Although he dazzled his Olympic rivals and thrilled the small crowd in the terraces, the poker-faced Kim played down his achievement.
"Getting the world record is very important but tomorrow's matches are more important," the 24-year-old told reporters through a translator as sweat dripped from his brow under a hot sun.
"It's just the ranking round...I want to focus on tomorrow, so today's not really big happy."
The ranking round determined the seedings for the men's individual event, which is decided on Aug. 12.
Kim's enthusiasm may have been tempered by the knowledge that Im failed to win the individual gold after setting his world mark with the Olympic recurve bow at London. The title went to another South Korean in Oh Jin-Hyek instead.
But the record should provide a massive spur for South Korea's bid to win the men's team gold on Saturday.
Kim will spearhead the top-ranked team featuring Lee Seung-yun and Ku Bon-chan, with the trio hoping to restore their nation's dominance in the event after their run of three Olympic titles from 2000-08 was broken by the United States in the semi-finals at London.
Former world champion Brady Ellison of the United States was also in excellent touch in the individual rankings round, shooting 690 to finish second, with Italian David Pasqualucci third with 685.
"It's really, really fantastic," Pasqualucci told reporters of Kim's record.
"I think three years or four years ago, only the compound (bow) can do 700.
"It's amazing...The conditions were good, really good today. Only the last two or three ends, maybe we had more wind but not really strong."