"It is with a broken heart that today (Sunday) I announce my resignation from Congress," Xinhua news agency quoted the California Democrat as saying in a statement released on Twitter on Sunday.
"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."
The resignation came several days after the House Ethics Committee began an investigation into allegations that Hill had violated House rules by engaging in a sexual relationship with a male congressional staffer, a claim she denied.
Hill, 32, admitted earlier this week to and apologised for an "inappropriate" relationship with a female campaign staffer before she was elected to Congress.
The controversy was triggered earlier this month when a conservative blog released intimate photos of Hill.
Hill, who has said she's going through a messy divorce and she is the victim of revenge porn by her estranged husband, called the publication of her photos an "appalling invasion of my privacy".
"It is also illegal, and we are currently pursuing all of our available legal options," she said in the statement on Sunday.
She added that the resignation "needs to happen so that the good people who supported me will no longer be subjected to the pain inflicted by my abusive husband and the brutality of hateful political operatives who seem to happily provide a platform to a monster who is driving a smear campaign built around cyber exploitation".
Hill defeated a Republican incumbent to represent California's 25th Congressional District in the 2018 mid-term elections.
( With inputs from IANS )