Filner was regretful and defiant during a City Council meeting as he explained the "the toughest decision of my life." He apologized to his accusers but insisted he was innocent of sexual harassment and said he was the victim of a "lynch mob."
"The city should not have to go through this, and my own personal failures were responsible and I apologize to the city," Filner said after the council voted 7-0 on a deal that ended a political stalemate after more than a dozen women publicly identified themselves as targets of unwanted advances, including touching, forcible kisses and lurid comments.
"To all the women that I've offended, I had no intention to be offensive, to violate any physical or emotional space," he said. "I was trying to establish personal relationships but the combination of awkwardness and hubris led to behavior that I think many found offensive."
Legal terms of the deal were being revealed as the council meeting continued into the late afternoon.
The 70-year-old Filner, a Democrat, served 20 years in Congress before becoming mayor of the nation's eighth-largest city.
He had previously insisted he still could be an effective mayor and underwent two weeks of behavioral therapy before returning to work this week.
But his support diminished as more women - one of them a great-grandmother and another a retired Navy admiral - came forward.
Some of Filner's closest political allies and all nine members of the council called on him to quit.
On Friday, just before the council vote, the Democratic National Committee took the extraordinary step of passing a resolution demanding Filner leave.
Dozens of people spoke for and against the mayor before the council convened behind closed doors to discuss terms negotiated by Filner and City Attorney Jan Goldsmith.
"Without the mayor's resignation, our city will continue to be paralyzed by this scandal, progress will be arrested and our focus will continue to be monopolized by this dark chapter in our history," said Laura Fink, a political consultant who accused Filner of patting her buttocks in 2005 when she was deputy campaign manager to the then-congressman.
Rachel Laing, a spokeswoman for an effort to recall the mayor, said petition gatherers have collected 20,000 signatures in five days to qualify for the ballot but that she would accept a deal for the mayor to resign.
"Every day he's in office is a day that the city remains in paralysis and that his victims suffer," she told the council.
Still, many who came to the special meeting supported the embattled mayor, hailing the liberal Democrat's work on behalf of civil rights and struggling minority groups.
"When my children ask me, 'Where were you when the public lynching of Mayor Filner took place?' I will tell them I was not an accessory," said Enrique Morones, president of immigrant advocacy group Border Angels.
Filner's biggest bargaining chip at the negotiating table was his refusal to resign.
The deal was negotiated between Filner, his lawyers, Goldsmith and two City Council members. It does not include attorney Gloria Allred, who represents Filner's former communications director, Irene McCormack Jackson, in a lawsuit filed against Filner and the city.
Allred said he City Council should not support it if in exchange for his resignation the city is going to use taxpayer money to pay Filner's legal bills.
"The mayor's resignation should not be bought at the expense of his victims," she said Thursday. "It would be morally wrong and hypocritical for the city to align itself with the mayor by helping him pay his legal fees."
McCormack, as she is known professionally, was the first woman to go public with allegations against Filner and her lawsuit is the only filed against the mayor and the city. McCormack claimed the mayor asked her to work without panties, demanded kisses, told her he wanted to see her naked and dragged her in a headlock while whispering in her ear.
Filner's troubles may also not be over. The San Diego County Sheriff's Department has interviewed the mayor's former communications director and opened a hotline to field any complaints about Filner. Investigators will deliver their findings to California attorney general's office to consider any possible criminal prosecution.
San Diego is not new to political scandals - Mayor Dick Murphy resigned in 2005 amid a financial crisis and Mayor Roger Hedgecock stepped down in 1985 after a felony conviction for conspiracy in connection with illegal campaign contributions - but even so Democratic consultant Chris Crotty said this has reached a new level.
When Filner's resignation takes effect, Todd Gloria, the Democratic City Council president, becomes acting mayor until a special election is held within 90 days. Democrats enjoy a solid edge over Republicans in voter registration, but the GOP will capitalize on the Filner debacle to try to reclaim an office it has held for nearly all of the last four decades.
After taking office on Dec. 3, 2012, Filner struck a five-year labor agreement with city unions and opened a city of San Diego office in Tijuana to strengthen ties with the Mexican border city, However, he alienated many key players even before the allegations surfaced, including members of the City Council, the city attorney and hoteliers.
The liberal Democrat served 10 terms in Congress, marked perhaps most famously by a 2007 run-in with a United Airlines baggage handler at Dulles International Airport that resulted in him acknowledging a misdemeanor charge of trespassing. Joanne Kunkel alleged in a criminal complaint that Filner barged past other customers, screamed at employees, repeatedly pushed her and yelled, "You can't stop me."
Filner, who began his political career on the San Diego school board and later served on the City Council, is twice divorced. Bronwyn Ingram ended her marriage engagement days before the scandal broke and later said Filner sent sexually explicit text messages to other women and arranged dates in her presence.
Associated Press writers Elliot Spagat and Michael R. Blood contributed to this report. Blood reported from Los Angeles.