[5][6] Petersen's early career included stints as a model and as a product demonstrator at FAO Schwarz; at the latter position, he briefly appeared during a Late Night with Conan O'Brien sketch filmed at the store.

[5] In 2008 Petersen worked for the Libertarian National Committee and the Atlas Network, assisting on the 2008 and 2012 presidential bids of former U.S. Representative from Texas, Ron Paul.

[5] He was an associate producer at the Fox Business program Freedom Watch with Judge Napolitano, which aired from 2010 to 2012, and later went to work as director of production at the conservative advocacy group FreedomWorks.

[7] Petersen served as an executive producer of the 2014 film Alongside Night, an adaptation of the novel of the same name which promoted agorism, an anarcho-capitalist political philosophy.

[citation needed] He ran for the United States Senate as a Republican in 2018, but was defeated in the primary by Missouri's Attorney General Josh Hawley.

By 2015, Petersen was living in Kansas City, Missouri, "behind a midtown QuikTrip" when he announced his candidacy in the 2016 Libertarian Party nominating convention for President of the United States.

[12][13] After Ted Cruz terminated his campaign for the Republican Party's nomination for president, Petersen received the backing of Mary Matalin and Erick Erickson.

[21] In September 2017, Petersen was banned from Facebook during his senate campaign for giving away an AR-15 style rifle as a promotion and criticizing his Democratic opponent Claire McCaskill's positions on gun rights.

[22] The ban was lifted after Fox News[23] and the New York Post[24] reported that Facebook's COO Sheryl Sandberg had made max donations to McCaskill's campaign.

[30] In the runup to the Republican primary election in August, President Donald Trump endorsed Petersen's rival Josh Hawley and campaigned for him.