Papadopoulos filed paperwork with the Federal Election Commission, declaring his campaign while tweeting he was interested in the seat in California's 25th district set to be vacated by Democratic Rep. Katie Hill.
"I'm smelling blood in the water now that Katie Hill has resigned. California's 25th congressional district is wide open for the taking," Papadopoulos wrote on Twitter. "Someone has to step up. I love my state too much to see it run down by candidates like Hill. All talk, no action and a bunch of sellouts."
Hill, 32, announced her resignation Sunday after the House Committee on Ethics announced it had opened an investigation into allegations that she engaged in an inappropriate sexual relationship with a congressional staffer in violation of House rules.
The freshman congresswoman denied the allegation but admitted to having had a relationship with the campaign staffer.
Last year, Papadopoulos was sentenced to 14 days in jail for lying to the FBI in its investigation into Russian interference in the 2016 presidential election.
Papadopoulos pleaded guilty to lying to the FBI about meetings with individuals closely associated with the Russian government during the campaign. Court documents stated he worked to create a relationship between the campaign and the Kremlin after then-candidate Trump secured the Republican nomination.