Don Lock, 79, died after a suspected road-rage confrontation on the A24 near Findon on Thursday evening.
Matthew Daley, 34, of St Elmo Road,  Worthing, who was arrested the next day, is due to appear before Crawley Magistrates' Court on Monday.
He has also been charged with possession of a knife in a public place in connection with the incident.
Mr Lock was attacked after getting out of his car following a "minor collision" with another vehicle. He died from stab wounds.
A knife was recovered following the stabbing.
His family gave a news conference on Saturday to pay tribute to the man they described as "gentle, kind and loving".
Mr Lock's son, Andrew, said the family had been "incredibly overwhelmed" by messages of support and they were "deeply grateful" to the people who had tried to treat his father at the side of the road.
The great-grandfather had recently celebrated his 55th wedding anniversary with his wife Maureen and had also been given the all-clear from cancer.
A man has been charged with murdering a great-grandfather who was stabbed after a car crash in West Sussex.