Neil Cicierega released three instrumental albums under the name "Trapezoid", which was changed retroactively to Deporitaz as an existing band called Trapezoid demanded that he change it. On the change to Lemon Demon, he said: "Eventually I started experimenting with singing, and once I felt ready to do that full time, I christened myself Lemon Demon and went into it head on.”
Since 2003, Cicierega has released seven full-length albums as Lemon Demon. In 2005, he and animator Shawn Vulliez released a Flash animated music video called "The Ultimate Showdown of Ultimate Destiny" on Newgrounds. This had over 12 million views on Newgrounds as well as topping the "Funny Five" on The Dr. Demento Show for several weeks and becoming the No. 1 Request for 2006.The song was later included in the 2006 album Dinosaurchestra. In April 2009, Cicierega released his first four albums as free downloads on his website. An updated recording of "The Ultimate Showdown of Ultimate Destiny" was released to the Rock Band Network in 2010.
In January 2016, Cicierega announced Spirit Phone, a full-length Lemon Demon album released on February 29, 2016. The album was the No. 1 best-selling album on Bandcamp for the first week of its release. On July 10, 2018, it was announced that copies of the album on CD, cassette, and vinyl would be sold through Needlejuice Records, who would later distribute remastered versions of Lemon Demon's EPs I Am Become Christmas, Nature Tapes, View-Monster, Dinosaurchestra, Damn Skippy, and Hip to the Javabean. "Touch-Tone Telephone" became Lemon Demon's most played song, the first to surpass "The Ultimate Showdown of Ultimate Destiny" and, as of December 2022, garnering over 50 million plays on Spotify
On June 19, 2020, Needlejuice Records released Needlejustice, a charity compilation album featuring 22 songs from artists they represent (including Lemon Demon) for the benefit of the NAACP Legal Defense Fund. Cicierega contributed a song to the album titled "Funkytown", which had originally been uploaded to his Patreon page in 2017. It features homages to popular songs from the 1970s and 1980s, including the titular "Funkytown" by Lipps Inc.