Guinness said that Valentim, aged 114 years and 313 days, is 48 days older than the world's former oldest human, Besse Cooper from Monroe, Georgia.
Cooper now holds the title of the oldest living North American.
Guinness verified that Valentim was born on July 9, 1896, in Carangola in the southeastern state of Minas Gerais, where she has always lived.
Known as "Grandma Quita," Valentim's family says she has a stubborn streak and has always made a habit of minding her own business. They also say her own father lived to be 100.
"She says she has lived long because she has always taken care of her own life -- and not the life of others," granddaughter Jane Ribeiro Moraes, 63, told a local newspaper.
Moraes added that Valentim has a great affection for feijoada -- Brazil's national dish, a hearty bean stew with various cuts of salted pork meat -- and chicken empada pastries "with a lot of hot sauce."
Craig Glenday, editor in chief of Guinness World Records, said Valentim represents an unprecedented feat for Brazil.
"To receive a claim from a woman born during the reign of Queen Victoria -- before the Ford Motor Company was formed, or before even George and Ira Gershwin, were born -- is remarkable in itself, but for that woman to be Brazilian makes it extra special. Never has a successful claim for longevity emerged from Brazil -- until now," he said.
Guinness said it has received several claims for potential "super centenarians" -- but none before were ratified because of a lack of evidence or documentation.
Bound to a wheelchair but mostly in decent health, relatives hope the attention for Valentim might help out her financial situation. They say the woman gets by on Brazil's minimum pension -- $335 a month -- and relies on the public health system, as the humble family can't afford to pay for private health insurance.
Valentim married her husband Joao in 1913, but he died in 1946. They had one son, four grandchildren, seven great grandchildren and five great-great grandchildren.