Guigar started his first daily comic strip, Greystone Inn, in February 2000 and built it to a readership of tens of thousands, both online and in newspapers. In 2005, he ended Greystone and launched Evil Inc, which continues to this day as an ongoing graphic novel.

Guigar won the ’Ringo Award for Best Humor Webcomic in 2023. That same year he was also nominated for a Silver Reuben for Best Longform Webcomic by the National Cartoonists Society. In 2007, Guigar was nominated for the Will Eisner Award for his journalistic comic, Phables, which ran in the Philadelphia Daily News.  The weekly podcast Guigar co-hosts with fellow cartoonist Dave Kellett, ComicLab, has more than 700,000 downloads and is often described as NPR’s Car Talk, but for cartoonists.