Among Simko’s instructors at the School of Visual Arts were Joe Orlando (VP of DC Comics and associate editor of Mad), Klaus Jansen, Sal Almendola, and Carmine Infantino.

[citation needed] After graduating from the School of Visual Arts, Simko held a full-time position as an artist for men’s neckwear, creating design pieces for ties.

[citation needed] Simko has created artwork for clients and organizations including Topps, Abrams Books, Reed Pop, FYE (retailer), IDW Publishing, Dynamite Entertainment, iam8bit, Southern Tier Brewing Company, Ride Snowboards, Sims Snowboards, Outlook Skateboards, The Gotham Girls Roller Derby League, Fangoria Magazine, New York Hardcore Tattoos, Spooky Empire's Ultimate Horror Weekend, Monster Mania, JLO Hangtag for Andy Hilfiger, and the NYC clothing boutique Live Fast.

[citation needed] His list of musical clients includes Metallica, The Misfits, GWAR, Less Than Jake, Trivium, Murphy's Law, Dwarves, Sonic Youth, Good Riddance, The Undead, Peelander Z, and others.

2009, Simko began his current career as writer/illustrator for the Topps Garbage Pail Kids and Wacky Packages brands, designing artworks for trading cards and licensed products.

An original story showcasing a group of wildly eccentric little kids also known as "little rotters" in the make-believe town of Pollilop Drop, The Sweet Rot is published by Schiffer Books.

In 2023, Simko designed a series of promotional character paintings and cereal box prop artwork for the Sci-Fi film Divinity, directed by Eddie Alcazar and produced by Steven Soderbergh.