The artist will take part in a 300-mile hike from Aberdeen to Ayr to raise awareness of autism.
He was diagnosed with a form of autism, Asperger's Syndrome, in 2009 and his daughter Lucy, 27, is also severely autistic.
Raven Russia, an investment company specialising in commercial property in Russia, where Howson's work is popular, has already donated £50,000 to his fundraising efforts.
Speaking at his Glasgow studio the 55-year-old artist, who has been in and out of psychiatric hospitals for much of his life and had a religious conversion in 2010 while about to take his own life, said: "My life has turned around. I have rediscovered serenity and now I see beauty in everything.
" I cannot wait to be out in the open and to embrace life to the full."
Asked if he was seeking solitude in some of Scotland's most tranquil places along the route, which he will start on April 2, he replied: "People with Asperger's normally can't interact socially, but I no longer want to be alone. I seek the company of good people and am looking forward to meeting local people at community events along the way. I hope that I will be joined on my walk by some of my friends."
His new partner Lorraine King, a former discus thrower whom he first met in 2010 when both were inpatients at the Priory psychiatric hospital in Glasgow, will accompany him for some of the walk; he has invited his friend the Doctor Who actor Peter Capaldi, who attended Glasgow School of Art at the same time as Howson, to join him.
Howson is working on a 35-painting commission for a benefactor in the Cayman Islands, and has just completed the sixth, entitled Jacob's Ladder.
He will complete a series of sketches and drawings along the Aberdeen to Ayr route, which covers the Aberdeen and Fife Coastal Paths, the Forth and Clyde Canal Walk, Clyde Walkway and he River Ayr Walk. However, he does not envisage a switch from figurative painting to landscapes.