Mary Kirk, 69, is walking from Canterbury to Rome, she is walking in support of refugees "who are travelling in the opposite direction to escape war and horror", and for the homeless in the UK.
Ms Kirk, from the Catholic Parish of St Edmunds in Bungay is an experienced pilgrim but has never taken on such a long challenge.
She will walk through France, Switzerland and Italy, starting on Sunday.
The trip is expected to last around three months.
The walk from Canterbury to Rome is a well-known route, called the Via Francigena.
Mary Kirk said: "As a Catholic, Rome is one of the cradles of my faith, and the seat of the Church in which I have chosen to remain a worshiper, despite its failings.
"My Camino experience has taught me that walking through a country is an excellent way to meet 'real' people, taste life there without the trappings of tourism."
She went on: "A pilgrimage is a journey to a place of spiritual importance and many who have done them will affirm that it is the process of travelling many hundreds, even thousands, of kilometres that has the most profound and transformative effect on them - rather than the achievement of arrival.
"The journey is within ourselves."
Pope Francis declared 2016 the Year of Mercy and encouraged pilgrimage.
Mary said: "A pilgrimage becomes a metaphor for life, with its ups and downs, joys and sorrows, pains and pleasures; with its turning upside-down of plans, its encounters with the unexpected; with the people who cross one's path, and the people with whom one walks a stretch and more.
"As in life, it is how one deals with all of this that brings to light one's true self, and the necessity of transformation.
"There is something about the steady daily plod, the rhythm of walk, eat, sleep; walk, eat, sleep that teaches a type of mindfulness, a living within the moment.
"There is space to think, or space to empty one's head; time to pray; and freedom to just be."
She said: "There is the liberty of the open road. I was an only, and a lonely, child, and I shall have been a widow for 30 years in 2016. For me to have to share - cramped dormitories, unisex washing facilities, enforced closeness - does not come easily, and is one reason I undertake these trips: it is good for me.
"There is drenching rain, burning sun, blisters, injuries, bed bugs, missed turnings and miles to return, exhaustion, and food that falls short in amount or nutritious value. It is life in all its fullness, and maybe also a life that gives a minute, privileged, and temporary glimpse into what it is to be less fortunate."
She finished: "I do feel slightly uncomfortable about the morality, or otherwise, of walking south with my nice rucksack and new boots, when so many are struggling in desperation to come north from the horrors of war and starvation."
