Lee is the founder and publisher of WildStorm, currently an imprint of DC Comics.

On February 18, 2010, Jim Lee was announced as the new Co-Publisher of DC Comics with Dan DiDio, both replacing Paul Levitz.

Lee was born in Seoul, South Korea, but grew up in St. Louis, Missouri. Lee's St. Louis Country Day School classmates predicted in his senior yearbook that he would found his own comic book company. But, initially, Lee seemed resigned to following his father's career in medicine. Lee attended Princeton University and obtained a degree in psychology with the intention of becoming a medical doctor. An elective course in Fine Arts reawakened his love for drawing; he graduated in 1986, putting medical school on hold to attempt a career in comic book illustration.

That same year, Lee traveled from St. Louis to a New York City comic book convention to show his work. Shortly thereafter, Lee was hired by Marvel Comics editor Carl Potts to work on the Marvel title Alpha Flight, seguéing from that title in 1989 to Punisher: War Journal. Lee's work on the Punisher was inspired by artists like Frank Miller, David Ross, Kevin Nowlan, and Whilce Portacio, as well as Japanese manga.

In 1989 Lee filled in for regular illustrator Marc Silvestri on Uncanny X-Men #248 and did another guest stint on issues #256 through #258 as part of the "Acts of Vengeance" storyline, eventually becoming the series' ongoing artist as of #267 when Silvestri left. During his stint on Uncanny Lee first worked with inker Scott Williams, who would become a long-time collaborator.

Lee's artwork quickly gained popularity in the eyes of enthusiastic fans, which allowed him to gain greater creative control of the franchise. In 1991, Lee helped launch a second X-Men series simply called X-Men, not only as the artist, but also as co-writer with long-time X-Men scribe Chris Claremont. Lee designed new uniforms for characters such as Cyclops, Jean Grey, Rogue, Psylocke and Storm, creating the images that an entire generation of X-Men readers would associate with the characters. He also co-created Gambit with writer Chris Claremont and the villain Omega Red with Brandon Choi. X-Men #1 is still the best-selling comic book of all-time with sales of 8 million copies of the first issue, although multiple purchases of variant covers illustrated by Lee accounted for part of the sales frenzy.

However, Lee ran into some creative hurdles. Claremont found it harder to work with Lee as their vision of the characters and storylines diverged. There was a prolonged power struggle over the future of the X-Men and in the end, Marvel X-Men editor Bob Harras favored the wildly popular Lee, causing Claremont to depart the new X-Men series with issue 3. Despite this, Claremont and Lee later reunited on various projects and are reportedly on friendly terms. Claremont and Lee even engaged in a mutual interview for Wizard magazine in 1995.

In 1992, Lee was one of six artists who broke away from Marvel to form Image Comics. Lee's group of titles was christened Wildstorm Productions and published Lee's pet title WildC.A.T.s, which Lee pencilled and co-wrote, and other series created by Lee in the same shared universe. The other major series of the initial years of Wildstorm, for which Lee either created characters, co-plotted or provided art for, included Stormwatch, Deathblow and Gen¹³.

Wildstorm would expand its line to include other ongoing titles whose creative work was handled by other writers and artists, some of which were spinoffs of the earlier titles, or properties owned by other creators, such as Whilce Portacio's Wetworks. As publisher, Lee later also expanded his comics line creating two publishing imprints of Wildstorm, Homage and Cliffhanger (that years later merged and were replaced by a single Wildstorm Signature imprint), to publish creator-owned comics by some selected creators of the US comics industry.

Lee and Rob Liefeld, another Marvel-illustrator-turned-Image-founder, returned to Marvel in 1996 to participate in a reboot of several classic characters; the project was known as Heroes Reborn. While Liefeld reworked Captain America and The Avengers, Lee plotted Iron Man and wrote and illustrated The Fantastic Four. Halfway through the project, Lee's studio took over Liefeld's two titles, finishing all four series.