Twice 4th World Tour "III" (stylized in all caps), or simply, III (read as "three"),[1] was the second worldwide concert tour and the fourth overall concert headlined by South Korean girl group Twice, in support of their third Korean studio album, Formula of Love: O+T=<3 (2021).

The tour began on December 25, 2021, at the Olympic Gymnastics Arena in Seoul, and concluded on May 15, 2022, at the Banc of California Stadium in Los Angeles, comprising 14 shows.

On October 1, 2021, an unnamed upcoming world tour was announced through the music video of "The Feels", the group's first English-language single.

[12] The arena North American leg of the tour wrapped up with an attendance of slightly over 100,000 attendees,[13] making them the first girl group to achieve this attendance milestone, and joining BTS as the only K-Pop act to garner over 100k tickets sold on their North American tour.

[15][16] This makes Twice the first-ever K-pop girl group to hold stadium shows in North America, proving their global success.