In a statement on Sunday, the 32-year-old freshman from the Los Angeles area says leaving the House is best for her constituents, community, and country.
Hill is under investigation by a congressional committee for an alleged intimate relationship with a male senior aide, which Hill denies.
She has acknowledged an affair with a young female staffer. Compromising photos and purported text messages surfaced online this past week in an American publication and a British tabloid.
Last year, Hill won the last Republican-held House seat anchored in Los Angeles County.