He is known for his long-lasting run on The Flash, as well as DC Comics events, Dark Crisis on Infinite Earths and Knight Terrors.
Along with his prolific work in the DC Universe, he has also written several Image Comics titles such as Nailbiter, Birthright, Ghosted and Dark Ride.
Williamson has also worked within the Energon Universe, alongside writer Robert Kirkman and writer/artist Daniel Warren Johnson, writing two five-issue mini-series, Duke and Cobra Commander.
[6] Following Infinite Frontier, Williamson wrote a sequel series, Justice League Incarnate, alongside Denis Culver.
[7] This 5 issue title followed the team Justice Incarnate, picking up from not only Infinite Frontier, but using plot-points and elements from Grant Morrison's Multiversity.
His tenure on Batman was short lived but lead to the crossover event, between the three ongoing-series Williamson worked on at the time, titled Shadow War.
[14] At New York Comic Con 2022, Williamson was announced to be the new writer on the new volume of Superman, where he would be joined by artist Jamal Campbell.
[17] Part of Dawn of DC, Williamson announced that he would be writing a Green Arrow 6 issue mini-series joined by artist Sean Izaakse in April 2023.
[19] In June 2024, Joshua Williamson announced in his online newsletter that he would be leaving both Batman & Robin and Green Arrow with issue #13 and #17/350 respectively, in order to free up his busy schedule, allowing him to write more series.