Nishikawa was mobbed by his team-mates after saving twice in the shootout in front of Urawa’s fans in Saitama, a nervy semi-final having ended 2-2 after 120 minutes when the home side grabbed a late leveller.
The final takes place in February against a team from the AFC’s western zone, with reigning champions Al Hilal of Saudi Arabia among the contenders.
Urawa, who won the Champions League in 2007 and 2017, had been prolific coming into the match, plundering 20 goals in their past four matches in Asia’s top club competition.
It looked like another goalfest when winger Yusuke Matsuo bundled in from close range on 11 minutes after a dangerous cross from full-back Hiroki Sakai.
But Jeonbuk, themselves two-time former champions, proved to be no pushover and were a threat on the break.
Former Leeds United and Swansea City winger Mo Barrow raced downfield and cut back for Song Min-kyu, who beat his man before rattling a fierce shot just over the bar.
The K League side needed extra time to reach the quarter-finals and semi-finals, and their coach Kim Sang-sik had called his players “really tired”.
But it was the visitors who finished the first half the stronger and 10 minutes into the second period Jeonbuk were level.
The ever-threatening Song was brought down in the box and after a prolonged VAR check, Paik Seung-ho squeezed in the resulting penalty.
They went to extra time and Jeonbuk thought they had defied fatigue to win it in the 116th minute, only for Urawa’s Danish forward Kasper Junker to grab a last-gasp equaliser in the 120th minute.
The knockout stages of this year’s Champions League in the eastern region of the draw have all taken place in Saitama and over one leg because of Covid.