She died peacefully in her sleep at Western Convalescent Hospital, according to the hospital's administrator, Emma Camanag. An autopsy is planned.
"It was a great pleasure and an honor taking care of her," Camanag said Friday. "She will be greatly missed."
The Shellman, Ga., native, whose father was believed to have been a slave, was born April 6, 1894, when the U.S. flag had only 44 stars and Ford's first car, the Model A, was nine years away.
Baines had outlived every one of her relatives. She married at a young age and later divorced. Her only child, a daughter, died of typhoid at 18.
Her image -- cinnamon lips turned up in a gentle smile and thinning hair tucked under a bright red bonnet -- was broadcast nationally in November when Baines, then the oldest person of African descent and the third-oldest person worldwide, cast her vote for Barack Obama as president.
The publicity escalated two months later, on Jan. 2, when 115-year-old Maria de Jesus of Portugal died and Baines was handed the title of oldest living person by the Gerontology Research Group, which verifies claims of extreme old age.
Reporters, photographers and camera crews descended on the quiet West Adams hospital that had been the supercentenarian's home since she broke a hip at age 107. Her feat made headlines around the globe.
Fellow senior citizens at the hospital, some approaching 100, said they longed for her longevity.
All the while, Baines slept away in her robe, now and then breaking from her routine of crispy bacon, Jerry Springer and church services to take interviews. The attention, the questions, the fascination people had with her age in her final year amused and perplexed her.
"Why all these questions?" she snapped at reporters once. "I want to know."
The question Baines seemed to like the least was the one she got the most. What's your secret? How have you stayed alive so long?
Each time, she shrugged her bent shoulders and referred people to God: "Ask him."
Aside from arthritis, Baines had been in good overall health until recently.
Growing up in Georgia while Jim Crow laws were in effect, Baines lived through a time when blacks were blocked from voting and subject to violent racism.
She lived in Ohio for some time and worked as a maid at Ohio State University. She then moved to California, where she settled in Los Angeles.
The supercentenarian lived alone with the help of a caretaker until she turned 107.
Her walls at the hospital were a shrine of birthday cards, honorary certificates and letters from the mayor, the governor and several presidents. Though church volunteers, relatives and fellow senior citizens kept her company, Baines rarely opened up to anyone other than her favorite caretaker, Cynthia Thompson.
On Thompson's days off, Baines often refused to get out of bed.
The two shared a strong bond. Thompson helped Baines change her robe, allowed her to wash her own face and respected her privacy. In return, Baines laughed at Thompson's jokes and opened up about long-ago days when she would ride to church in a horse and buggy.
She told Thompson she was not afraid to die. Only of being alone.
As she rang in her final birthday April 6, Baines was anything but that.
More than a hundred people crowded around her at the hospital to celebrate her birthday. Giant balloons, flowers, certificates and best wishes from President Obama and Gov. Arnold Schwarzenegger poured in.
Baines, wearing pearl earrings, took it all in and nodded in approval.
With her passing, Kama Chinen, a 114-year-old Japanese woman born May 10, 1895, is now the oldest person in the world.
Baines will be buried at Inglewood Park Cemetery.