Porter was born in England and traveled to the United States around the age of one with her family.^[1][2] By age 15, she was working as a prostitute in San Antonio, Texas.^[1][2] By the age of 20, she had started her own brothel.^[2] She became extremely popular for having a cordial and sincere attitude, choosing only the most attractive young women as her "girls", requiring that her "girls" practice good hygiene, and for maintaining an immaculate personal appearance.^[3] Her brothel was located at the corner of Durango and San Saba streets, better known as the Sporting District.^[1][2][4][5]

By 1895, her brothel in San Antonio was one of the more popular in the Old West.^[3] It had become known as a frequent stop-off for outlaws. Butch Cassidy, the Sundance Kid, Kid Curry, and other members of the Wild Bunch gang frequented her business.^[1][2] Della Moore, one of her "girls", became the girlfriend of Kid Curry,^[2] remaining with him until her arrest for passing money from one of his robberies (she was arrested but acquitted, eventually returning to work for Porter once again). In 1899, Porter's lease was canceled by the owner of the building, Luther Bounds, who was expanding his gambling and saloon business. Porter then devised what is believed to be the first "call service", in Texas for prostitutes by managing a network of runners and delivery boys to carry requests and telegrams for girls back and forth from local saloons, telegraph offices and casinos to her rented room at a boarding house, from where she would assign girls based on her knowledge of the client.

Lillie Davis, another of her "girls", became involved with outlaw and Wild Bunch member Will "News" Carver. She later claimed she had married Carver in Fort Worth before he died in 1901, but no records to verify the alleged marriage.^[3] The Sundance Kid and his girlfriend, Etta Place, whose true identity and eventual disappearance from history has long been a mystery, first met while she worked for Porter, but this may have never been confirmed.^[1] Wild Bunch gang member Laura Bullion is believed to have worked for Porter between 1898 and 1901.^[2]

Porter was well respected for her discretion, always refusing to turn in a wanted outlaw to the authorities.^[3] She also was known for being extremely defensive of her "girls", insisting that any who mistreated them never return to her brothel.^[3] She generally employed anywhere from five to eight girls, all ages 18 to 25, and all of whom lived and worked inside her brothel.^[3] Her business was popular with outlaws of the day as well as with lawmen, and she made sure that any lawmen who entered received the best treatment.^[3] William Pinkerton, of the Pinkerton National Detective Agency, visited her.^[1]

By the early 20th century, the tide had begun to turn against active, openly operating brothels. Porter had been arrested in 1888 and 1891, but the investigation into her affiliation with the Wild Bunch and a canceled lease led her to move her operations to her home in 1901.^{[6][self-published source]} Eventually, she retired and faded from history. It is not known where she went after her retirement. Most agree that she retired semi-wealthy. Some stories indicate that she married a man of wealth, some indicate she retired into seclusion, and others indicate she returned to England. None of those are confirmed. Later rumors indicated that she lived until 1940, when she was killed in a car accident in El Paso, Texas. However, this also is not certain.^[1][2]

• Selcer, Richard F. "Porter, Fannie". Handbook of Texas Online. Texas State Historical Association.