Hill, 32, is fighting off multiple allegations which she describes as politically motivated, blaming the controversy on her husband, Kenny Heslep, who she is in the midst of a bitter divorce with.
In an official statement put out by Hill, she wrote:
"It is with a broken heart that today I announce my resignation from Congress. This is the hardest thing I have ever had to do, but I believe it is the best thing for my constituents, my community, and our country."
It is with a broken heart that today I announce my resignation from Congress. This is the hardest thing I have ever had to do, but I believe it is the best thing for my constituents, my community, and our country.— Rep. Katie Hill (@RepKatieHill) October 27, 2019
See my official statement below. pic.twitter.com/nG97RQIwvO
The allegations surfaced after the release of intimate photos of her on the conservative website RedState.org, which also alleged that Hill had more than one inappropriate relationship with staff members. The same website posted a nude picture, reportedly involving her and one of her female campaign staff members.
Hill represents parts of northern Los Angeles and eastern Ventura counties.
The House ethics committee had launched an investigation into whether Hill had an inappropriate relationship with an aide in her congressional office, which is prohibited under House rules.
But her relationship with the campaign aide became a concern for House Democrats who have made equality in the workplace a particular priority. On Sunday, after apologizing for the relationship with a subordinate, Hill announced she was stepping aside.
Hill's statement provided no details on that or when she would step down. Hill's office and campaign provided no additional public comment.
Hill was elected by 9 percentage points last year, ousting two-term Republican Rep. Stephen Knight and capturing the district for her party for the first time since 1990.
The Associated Press contributed to this report.