Adam Kubert began his comics career as a letterer for DC Comics. His first credited artwork for the company is the story "Gremlins" published in Sgt. Rock #394 (Nov. 1984). In 1988, Adam Kubert drew the Jezebel Jade limited series, a spin-off from the Jonny Quest series, for Comico. He collaborated with his brother on Adam Strange (1990) and the Batman versus Predator intercompany crossover (1992).

Adam Kubert is known for his work at Marvel Comics. From 1993 to 1996 he illustrated 17 issues of Writer Larry Hama's run on Wolverine between issues #75 to 102. His first issue on the series featured the after affects of Magneto removing the adamantium from Wolverine's body. Kubert drew the Weapon X limited series as part of the "Age of Apocalypse" storyline in 1995. The following year, he drew the Onslaught: X-Men and Onslaught: Marvel Universe one-shots which lead into the "Heroes Reborn" crossover. From 1997 to 1998 he illustrated 12 issues of Peter David's run on The Incredible Hulk from #454 to 467, as well as the -1 issue (July 1997). From late 1998 to early 1999 Kubert drew X-Men #81 - 84, on which he was teamed up with European colorist Richard Isanove, who subsequently followed Kubert to Ultimate X-Men, employing the pencils-to-color approach seen on most of Ultimate X-Men covers.

In 2001, Kubert drew the new Ultimate X-Men title, penciling the first four issues, and then illustrating 16 various issues beginning with #7, before leaving the title with issue #33 (July 2003). In 2004, he began a run on Ultimate Fantastic Four, once again with Writers Mark Millar and Brian Michael Bendis, illustrating that series' first six issues, and then issues 13-18.

Both Adam and his brother Andy signed exclusive contracts with DC Comics in June 2005. Kubert's first project for DC was illustrating "Last Son", a Superman story arc co-written by Geoff Johns and Richard Donner, which ran in Action Comics #844–847, 851 and Action Comics Annual #11. Further delay forced DC Comics to bring in substitute creative teams and delay the fourth part of the "Last Son" storyline and the 3D issue to #851, which was released in early July 2007. The final part of the storyline was in Action Comics Annual #11. Following his work on Superman he penciled the "Final Crisis" tie-in, DC Universe: Last Will and Testament, written by Brad Meltzer.

Kubert was rated by Wizard magazine as one of the "Hot 10 Writers and Artists" in the industry in 2008. He is the son of Joe Kubert and brother of Andy Kubert, both comic book artists as well, and the uncle of comics Editor Katie Kubert. Born in Dover, New Jersey he is an instructor at the Joe Kubert School located there, which Joe Kubert founded, and at which he and Andy studied.

May 2009 marked Adam Kubert's return to Marvel, his first interior work being published as one of two stories in Wolverine #73 and 74. Following this he contributed several covers to New Mutants and Wolverine: Weapon X, and penciled the "Dark Reign" tie in, The List: Amazing Spider-Man.

Kubert and his brother Andy teach at The Kubert School, which was founded by their father, who also taught there before his passing in 2012.

In June 2017, Kubert began penciling Peter Parker: The Spectacular Spider-Man written by Chip Zdarsky. The revamped title being billed as a “back-to-basics” approach for the character.