When Stephens first pitched the show, it was called Cryptids, after the monsters undiscovered by science. It involved a crack team of globe-trotting cryptozoologists that were uniquely qualified for the job because they were once cryptids themselves. Okapi, Komodo, and Megamouth, along with their 9-year-old human mascot, Francis, served as a sort of anti-detective team. They scooted across land, sea, and air in what Stephens called a Campercopter and their goal was to preserve the mystery of the Earth's strangest creatures before they were exposed by humans or destroyed by the cryptids' nemesis, Monsieur Dodo. This version got him nowhere with many networks, though they all did show interest for some time.
Months later, the show was picked up by Cartoon Network, due to the network (at the time) wanting more action shows due to the success of Ben 10 and Ben 10: Alien Force. 9-year-old Francis became 11-year-old Zak Saturday and many of the original characters were canned. For a time, the network wanted the show's name to be The Secret Adventures Of Zak Saturday, but it was later changed. Unlike most mystery shows, the goal of the heroes of The Secret Saturdays is not to reveal the existence of cryptids, but to hide it. The art style of the show was influenced by the artwork of Alex Toth and 1960s Hanna-Barbera action cartoons, such as Jonnny Quest and The Herculoids.
In July 2008, Cartoon Network started a viral campaign for the show. Several commercials for a website called CryptidsAreReal.com aired on Cartoon Network. Each commercial featured a pet of the Saturday family: one showed Komodo, another Fiskerton, and a final one showed Zon. One area of the program's website also held a "secret" document: while most of the words on it were blacked-out, the names of Drew and Doc (two of the main characters) were revealed. The document also talked about a creature discovered outside of Nottinghamshire, England. Though the first word was blacked-out, the paper said a "phantom" had been the newly discovered creature. It was implied that the creature was the Fiskerton Phantom, a cryptid reported to have lived outside of Nottinghamshire and commonly done by this website, would be Fiskerton, a main character in the show. To back this conclusion up, Zak stated in one episode that Fiskerton was lucky because he was saved by Doc and Drew, also stated in the document. Typed at the bottom of the document was the name "Agent Epsilon". This is a character in the show. The website also showed a blueprint of the Saturdays family's airship. Another site was linked to CryptidsAreReal.com: the page for an organization called Ten Hero Tusk (an anagram of "the Kur stone"), which states that its explorers are "D. Blackwell, B. Finster, and L. Van Rook", all of which are characters in the show. During San Diego Comic-Con 2008, booklets about a show called Weirdworld (the show-within-a-show) were given out, with the website for it on the back of them. Unlike CryptidsAreReal.com, this one couldn't be traced back to Cartoon Network. Later, commercials for Weirdworld aired on Cartoon Network for a few weeks before a commercial for The Secret Saturdays itself was aired on October 3, 2008.
A DVD featuring the first five episodes of the series (along with bonus features such as animatics) was released on July 21, 2009. A second DVD with similar features was released on October 27, 2009. An encyclopedia entitled The Secret Saturdays: The Official Cryptid Field Guide was released on August 11, 2009. Graphic novels and chapter books were released by Del Ray Manga in Summer 2009. A video game called The Secret Saturdays: Beasts of the 5th Sun was released by D3 Publisher for the PlayStation 2, PlayStation Portable, Nintendo DS and Wii on October 20, 2009. Comic adventures of The Secret Saturdays appear semi-monthly as part of Cartoon Network Action Pack comic books published by DC Comics. A line of action figures and play sets was released by Mattel.