According to his identity card Celino Villaneuva Jaramillo was born in 1896, four years before current Guinness world record holder Nabi Tajima was born.
Mystery surrounds the background of Mr Jaramillo, known affectionately as Don Celino, who turned up at the home of Marta Ramirez aged 99 and has stayed there ever since.
The destitute ex-farm worker had been left with nothing after his house burned down, destroying his possessions including his original birth certificate.
And Ms Ramírez admitted she did not expect the frail man, who is now blind, deaf and cannot walk without help, to still be living with her 20 years later.
She told the Guardian: “He was 99, I didn’t think he’d be around that much longer.”
Chile’s office of statistics has confirmed Mr Jaramillo is 121 despite questions surrounding his date of birth.
Demographic department head Jacqueline Salinas said: “Checking our records, Celino Villanueva Jaramillo was effectively born on 25 July 1896 – and he’s still alive.”
When Mr Jaramillo turned 115, the country’s president Sebastián Piñera flew out to meet him and drop off presents for the country’s oldest resident.
Mr Jaramillo was born in Rio Bueno in the same year the first modern Olympics were held and Queen Victoria become the UK’s longest-serving monarch.
The farm labourer, who never married, spent the last three decades of his working life working for a boss who sacked him on his 80th birthday.
After that he moved to Mehuin, a small town beside the Pacific, where he made money by selling vegetables.
But he was left homeless following the house fire and now lives with Ms Ramírez.
The record-breaking resident is now 90 per cent blind because of cataracts, 85 per cent deaf and has no teeth left.
Japanese woman Nabi Tajima is officially the world’s oldest living person, at the comparatively sprightly age of 117.