[3] At 11 years old, he said, he got his first paying job as an artist, drawing for a coloring book company, and as he grew older did art for a variety of outlets including Larami Toys, the afterschool-TV show Wee Willie Webber Colorful Cartoon Club on Philadelphia's WPHL-TV, and for a holiday card manufacturer.

He drew four "I ... Vampire" stories in the House of Mystery series[5] and pencilled stories in such similar DC titles as Ghosts, The Unexpected, and Weird War Tales through the early 1980s, and made his superhero debut penciling an eight-page "Tales of the Green Lantern Corps" backup feature in Green Lantern #154 (July 1982).

[4] After co-penciling Justice League of America #212 (March 1983) with Rich Buckler, and making his cover debut with The Daring New Adventures of Supergirl #7, Cullins penciled his first full-length comic, Blue Devil #1 (June 1984), starring a superhero he had co-created with writers Gary Cohn and Dan Mishkin earlier that month for a backup feature in The Fury of Firestorm #24 (June 1984).

Cullins and writer Len Wein produced a Ted Kord Blue Beetle series[9] for DC, which had acquired the character from the defunct Charlton Comics.

He was still freelancing primarily for DC, collaborating there with writer J. M. DeMatteis on a six-issue miniseries revival (Feb.–July 1988) of Jack Kirby's The Forever People,[11] penciling the stories and covers.

With writer Mark Evanier, primarily, Cullins co-plotted and penciled issues #1–9, 11–12, and 15–18 (collectively, Feb. 1989–July 1990) of a revival of Kirby's The New Gods.

[6] Teamed with writer Fred Burke, Cullins penciled stories and covers for all nine issues of the superhero-team comic Hyperkind, for Marvel's Clive Barker–created Razorline imprint.

Cullins contributed a one-page Blazin' Glory pinup to Atomeka Press' A1 Sketchbook (Nov. 2004), his last known comics work as of 2007.