Munroe was a fan of the funny pages from an early age, starting off with Calvin and Hobbes. After graduating from the Chesterfield County Mathematics and Science High School at Clover Hill: A Renaissance Program, he graduated from Christopher Newport University in 2006 with a degree in physics. Munroe worked as an independent contractor for NASA at the Langley Research Center before and after his graduation. In January 2006 NASA did not renew his contract and he began to write xkcd full-time. He now supports himself by the sale of xkcd related merchandise. The webcomic quickly became very popular, garnering up to 70 million hits a month by October 2007.

He has also toured the lecture circuit, giving speeches at such places as Google's Googleplex in Mountain View, California.

Munroe lives in Somerville, Massachusetts and has two brothers: Doug and Ricky.

[[Image:Webcomic xkcd - Wikipedian protester.png|thumb|right|350px|" Wikipedian Protester", with title-text " THE CONSTITUTION"]]xkcd is a stick figure comic with themes in computer programming, mathematics, science, language, and romance.

Munroe had originally used xkcd as an instant messaging screenname because he wanted a name without a meaning so he wouldn't eventually grow tired of it. He registered the domain name, but left it idle until he started posting his drawings in September 2005. The comic has a very loyal fanbase. Munroe said, "I think the comic that's gotten me the most feedback is actually the one about the stoplights".

Munroe licenses his creations under the Creative Commons attribution-noncommercial 2.5 license, stating that it isn't just about the free culture movement, but that it also makes good business sense. His income derives from the sale of merchandise to his fans, sales consisting of thousands of t-shirts a month.

Munroe is the creator of the websites "BestThing", "The Funniest", and "The Fairest", each of which presents the user with two options and asks them to choose one over the other.

He started the "WetRiffs" website as a joke, one month after drawing the "Rule 34" comic, "lamenting the lack of guitar-in-the-shower pictures on the internet."

LimerickDB encourages the creation of new and the collection of old limerick.

Most recently he started a Geohashing wiki based on one of his comics which contains an algorithm that generates pseudo-random coordinates around the world every day.

Aside from maintaining his websites, Munroe also engages in kite photography, in which cameras are attached to kites and pictures are then taken of the ground or buildings.