Mikado City, an otherwise peaceful city, is suddenly invaded after a gate from another world opens seemingly from nowhere. Interdimensional monsters called Neighbors attack, man-made weapons prove to be ineffective against them, and the city is quickly destroyed. When all hope appears to be lost, a mysterious group known as the Border Defense Agency begins to retaliate using specialized technology called Triggers and manages to halt the invasion. Four years later, the organization continues to protect the populace of Mikado City and are now revered as heroes.

Yuuma Kuga is a new student at First Mikado City High School—a school associated with Border—which comes as a surprise, as transfers to the dangerous areas are seen as suspicious. He is soon targeted by bullies, but Border's member-in-training Osamu Mikumo stands up for Yuuma, despite his doubts about him. The two's situation turns grim when a Neighbor arrives from a gate that abruptly opens in the forbidden zone; while Osamu struggles to fend it off with his Trigger, Yuuma defeats it with ease. As Osamu inquires about Yuuma's position in Border, it turns out that Yuuma is no agent—but a Neighbor himself.

World Trigger was temporarily put on hiatus in November 2016 due to the author's poor health. The manga continued serialization on October 29, 2018.

The series has been published in English by VIZ Media under the Shonen Jump imprint since October 7, 2014. It has also been simulpub digitally through MANGA Plus. World Trigger has been published in French by Kazé since October 22, 2014; and in Italian by Edizioni Star Comics since January 10, 2015.

The manga was adapted into a Japanese live stage play titled World Trigger the Stage, which was shown from November 19, 2021, to November 28, 2021. A sequel show titled World Trigger the Stage: Daikibo Shinkouhen was performed from August 5, 2022, to August 14, 2022. Two video games based on the series were released; developed by Artdink, World Trigger: Borderless Mission was published on September 17, 2015, for the PlayStation Vita. A smartphone game titled World Trigger: Smash Borders was developed by Ganbarion and published on July 21, 2015; it was later rereleased for the PlayStation Vita on February 17, 2016.