Rucka's writing career began with the Atticus Kodiak series. Kodiak is a bodyguard whose jobs are rarely as uncomplicated as they at first appear. The series to date consists of Keeper, Finder, Smoker, Shooting at Midnight, Critical Space, Patriot Acts, and Walking Dead. These works garnered Rucka much critical acclaim and comparisons to the elite writers of crime/suspense fiction. The "Atticus" novels are notable for their realism and attention to detail, which is partly a product of Rucka's fight training and experience as an EMT. He has written six non-Atticus books: Fistful of Rain, Alpha, Bravo, A Gentleman's Game, Private Wars, and The Last Run; the latter three are tie-ins to his comic book series Queen & Country.
In 1998, Rucka entered the comics industry with Whiteout, published through Oni Press. Whiteout focuses on a murder in an Antarctic base. It was followed by a sequel, Whiteout: Melt.
The majority of Rucka's work throughout the 2000s was for DC Comics, where he was involved with their main trinity of characters: Superman, Batman and Wonder Woman. Rucka wrote Batman on a regular basis in the Detective Comics series following the events of "No Man's Land'". He wrote the novelization of the year-long arc. While writing Detective Comics, he created a number of background characters that led to the co-creation of Gotham Central with co-writer Ed Brubaker. His Batman work includes such story arcs as "Bruce Wayne: Murderer?" and "Bruce Wayne: Fugitive" as well as the Batman: Death and the Maidens limited series. From October 2003 to April 2006 he wrote Wonder Woman after having previously written the character in the Wonder Woman: The Hiketeia original graphic novel.
From 2002 to 2004, he did some work for Marvel, including the start of the third volume of Wolverine, Elektra and the mini-series Ultimate Daredevil and Elektra. He has worked for Image Comics. The first volume of his series Queen & Country concluded in July 2007 with issue #32.
He co-wrote Countdown to Infinite Crisis, a one-shot and the official start of the Infinite Crisis storyline, with Geoff Johns and Judd Winick.] Rucka's work on both Wonder Woman and Gotham Central ended in 2006. Although he was not involved in the main storyline of Infinite Crisis, he did write The OMAC Project which built towards the event, focusing on Batman's distrust of other superheroes. This led to the revival of Checkmate, a UN authority that oversaw superheroes including Sasha Bordeaux, an integral character of The OMAC Project. He was a co-writer on the weekly series 52, which he co-wrote with Geoff Johns, Grant Morrison, and Mark Waid. This series chronicled in real-time the year following Infinite Crisis and saw Rucka focus on Renee Montoya of Gotham Central and the creation of the new Batwoman, Kate Kane. Rucka returned to the Batwoman character frequently over the years in a 52 sequel The Crime Bible and Final Crisis: Revelations before returning to the character in Detective Comics with artist J. H. Williams III, as well as reviving Renee Montoya in the book's second feature with artist Cully Hamner.
Rucka wrote the screenplay for the "Crossfire" segment in the direct-to-DVD anime Batman: Gotham Knight, in which Crispus Allen, a character he created, appears. In 2009, Rucka and artist Eddy Barrows took over Action Comics as the title moved its focus from Superman to Kryptonian heroes Nightwing and Flamebird in the aftermath of the "New Krypton" story arc. As well as writing Action Comics, Rucka co-wrote the main New Krypton 12 part series with Superman writer James Robinson.
At Wondercon 2010 Rucka announced he would part ways with DC Comics to focus on his own projects, in part because of DC's failure to keep him on as writer of Wonder Woman: Earth One as promised. Rucka then wrote The Punisher for Marvel Comics.
On July 11, 2011, Rucka launched the webcomic Lady Sabre and the Pirates of the Ineffable Aether, a steampunk adventure series illustrated by Rick Burchett. New installments appear every Monday and Thursday. In May 2013, Rucka launched a Kickstarter campaign to fund the publication of a print edition of Lady Sabre and achieved its initial funding goal of $27,500 within eight hours.
He wrote the creator-owned series, Black Magick, which was drawn by Nicola Scott and published by Image Comics. The Rucka/Scott creative team produced a new Wonder Woman series for DC Comics in June 2016 as part of the DC Rebirth relaunch. Rucka concluded his run on Wonder Woman as of issue #25.
In July 2019, Rucka began writing the Lois Lane 12-issue limited series with artist Mike Perkins.