Rosa Santos was born in Tremembé, São Paulo, Brazil, on 7 February 1915. Her mother, Carolina, arrived in Taubaté in 1891 at the age of 5. She was born in Lombardy, Italy. Her father, Barnabé, was born in Tremembé in 1877. In 1908, the two married and went on to have 8 children. Gracia was their third child, followed by Rosa in 1915. The two sisters were inseparable and assisted their mother in caring for their 4 younger siblings.

At some point, the family moved to a large house in the city center, constructed by their father. However, with the onset of the Second World War and the passing of their father, new challenges arose. As a result, some family members had to move to the city of São Paulo in search of better job opportunities. Their mother moved to São Paulo with five of her children, while the other three remained in Taubaté. Rosa took an embroidery course, later working from home. Eventually, all siblings moved out, leaving Rosa and their mother alone in the family home. In 1954, their mother passed away, leaving Rosa alone to manage the household. Three years later, when her youngest sister welcomed her first child, she went to assist with childcare. Despite intending to return home afterward, her sister insisted Rosa stay with them, as she would otherwise be living alone upon returning to São Paulo.

From 2011 onwards, both she and Gracia relied on a caregiver, and in 2016, they moved into a nursing home.

Rosa Santos passed away in São Paulo, São Paulo, Brazil on 29 March 2024, at the age of 109. She is survived by her older sister, as well as several nieces and nephews.