Jeffrey Long set off from Bradford City Hall on March 10 in aid of the Royal British Legion (RBL) and the Support Our Paras charity.
Mr Long, from Bingley, West Yorkshire, will turn 90 later this year and has raised more than £300,000 for charity over the last 14 years.
He said: “It has been heavy going at times, due to a bad back and an ankle injury from my days as a para, so I’ve had to push myself at times.
“But it has been wonderful meeting so many friendly faces and supporters whilst out on my walk, and that has really helped to keep me going.”
The great-grandfather, who was a paratrooper from 1952 to 1957, is walking 100 miles for the RBL, to mark their centenary year, and 90 miles for Support Our Paras.
He said: “I am very proud of my time as a paratrooper, and this is just my way of giving something back.”
Despite having daily chemotherapy and still suffering back pain from a training injury in 1954, Mr Long is hiking around the hills above Bingley to complete the challenge.
So far, he has raised more than £1,600 and is hoping to finish in time for the RBL centenary on May 15.
Mr Long began fundraising in 2007 when he marched 650 miles from London to Lausanne in Switzerland in 39 days, carrying a 30kg backpack, to raise money for the RBL.
Since then, he has completed dozens of charity hikes, including 100 miles along the south coast to support the RBL.
He attracted celebrity support after his fundraising efforts went viral in 2017, when comedians Jason Manford and Iain Lee used social media followers to swell Jeffrey’s JustGiving page from less than £500 to more than £120,000 in aid of the RBL.
Natalie Urbaniak, the fundraising and communications manager for Support Our Paras, said: “It’s wonderful to have Jeffrey supporting us and his airborne brothers once again this year.
“Despite sustaining a back injury from a parachute malfunction in 1954 when he was serving with the 12th (Yorkshire) Parachute Battalion, Jeffrey has proven that he is still ‘ready for anything’ all these years later.
“He has overcome a lot with his health in recent years but is determined to carry on with his fundraising walks to help those in need.”
Tina Pringle, the Royal British Legion’s community fundraiser for West Yorkshire, said: “Jeffrey is one of our most remarkable fundraisers, and we are delighted to have his support.
“He has dedicated his retirement to raising money for our armed forces community, so we hope that everyone gets behind his latest challenge.”