The IWGP World Heavyweight Championship (IWGP世界ヘビー級王座, IWGP Sekai hebī-kyū ōza) is a professional wrestling world heavyweight championship owned by the New Japan Pro-Wrestling (NJPW) promotion.

"IWGP" is the acronym of NJPW's governing body, the International Wrestling Grand Prix (インターナショナル・レスリング・グラン・プリ, intānashonaru resuringu guran puri).

After a fan vote, it was decided that Naito, White, Ibushi, and Heavyweight Champion Kazuchika Okada would compete at Wrestle Kingdom 14 on January 4–5, 2020, where one would end up with both titles.

[3] Naito achieved the feat to become the first "Double Champion" and the two titles were defended together since (apart from one time).

[5] On March 1, 2021, with Ibushi still champion, the unification of the titles to create the new IWGP World Heavyweight Championship was officially announced, with Ibushi as the inaugural World Heavyweight Champion.