In its annual billionaires list, Forbes estimated her wealth at some €20 billion, making the 98-year-old, from Cuneo in Piedmont, not just Italy's richest person but the 30th richest person in the world.
Fissola is also the world's fourth richest woman and takes her place in the list after inheriting the wealth of her husband Michele, who died on Valentine's Day last year.
In spite of her extraordinary wealth, little is known about Fissola's private life.
A polyglot who speaks three languages, she met her husband while working as a secretary and translator at his chocolate empire Ferrero, which is today world famous for its Nutella spread and Kinder eggs.
The pair married in 1963.
Her late husband, the son of a small-time pastry maker, started from humble beginnings and made his fortune using ground hazelnut to make Nutella in a bid to save money on chocolate amid rationing during the Second World War.
Today, Ferrero is the world's fourth-largest chocolate maker.
The company is based in Alba and operates 18 production plants globally, selling its chocolate products in over 100 countries. The current CEO is Giuseppe Ferrero, the couple's son.
But Fissola was by no means the only Italian on the rich list.
Hot on her heels in 37th place came the 80-year-old-founder of the eyewear company Luxottica, which makes Ray Ban and Persol sunglasses.
Forbes estimated his net worth at a cool €17.7 billion.