The announcement comes a day after Kane was convicted on charges of perjury and obstruction. Critics had called for her to step down right away.
The resignation will be effective at the close of business Wednesday. The new acting attorney general will be Bruce L. Castor Jr., Kane's top deputy, office spokesman Jeffrey Johnson said.
In the statement, Kane said: "I have been honored to serve the people of Pennsylvania and I wish them health and safety in all their days."
Kane will be sentenced later. The felony offense of perjury carries a potential jail term, and prosecutor Kevin Steele said jail time may be recommended.
"It seemed that we had somebody who felt that she was above the law, and that's not the case because no one is above the law," he said. "We are a very honorable profession here. We have rules that we have to abide by and there are no exceptions to that."
Kane, a Democrat elected in 2012, had denied leaking confidential information about grand jury deliberations to the media in an effort to harm her predecessor and then attempting to cover it up.
Defense attorney Gerald Shargel told reporters outside the court that the verdict was "a crushing blow."
"We will continue this litigation, we will continue this fight because we believe that our client has been wrongfully accused of misconduct," he said.
The criminal charges
were filed against Kane in August 2015. They alleged that Kane acted on anger about a local newspaper article that accused her of dropping an investigation into politicians accepting bribes.
To get back at her predecessors, the complaint said Kane leaked sealed, confidential grand jury documents to the media and then lied under oath.
Kane said in an August 10, 2015, statement that a campaign of political retribution had been launched against her long before the allegations at the center of the criminal complaint.
The entire episode, Kane claimed, began with a series of "pornographic, racial and religiously offensive emails" from the office of former Attorney General Tom Corbett -- who was elected governor in 2010 -- and uncovered in an investigation.
She called for the release of the emails, but Judge William Carpenter blocked the move under what Kane called "a tortured interpretation of our state's grand jury secrecy law."
Her attorney addressed the issue with reporters after the verdict.
"We believe that our defense was compromised, and we will fight that till the end," Shargel said.
"We have arguments to make on whether this trial was fair. We intend to pursue all arguments that are available to us. We're not going to walk away from any arguments."
In a statement Monday, Pennsylvania Gov. Tom Wolf said the charges were "unbecoming of the Commonwealth's top law enforcement officer."
"As I have made clear, I do not believe Kathleen Kane should be Attorney General of the Commonwealth of Pennsylvania. I believed this when she was charged, and today, after conviction, there should be no question that she should resign immediately," Wolf said in a statement.
"While there is no simple procedure to remove a civil officer, the Office of Attorney General and its employees, as well as the people of Pennsylvania, deserve to move on. I implore Attorney General Kane to do what is right: put the commonwealth's residents first and step down from office."
Kane had resisted earlier calls to step down, saying resignation would be an admission of guilt "and I'm not guilty."
After Kane's conviction, Pennsylvania Republican Party Chairman Rob Gleason said it was "a terrible day for the commonwealth."
"It is time to bring honor and respect back to the office of the attorney general," Gleason said.