Prost won his last title in 1993, by which time he had taken the chequered flag first in 51 Grand Prix.
In recent years 57-year-old Prost has driven for Renault subsidiary Dacia in European ice-racing events with considerable success, winning the Trophy Andros last month in a Dacia Lodgy.
Throughout the year, Prost will take part as a Renault driver in sports demonstrations and also as a representative at Renault events.
"Renault's history is intimately linked to that of motorsport and I have a deep attachment to the brand, with which I achieved some of the greatest successes in my sporting career," said Prost.
Carlos Tavares, Renault's chief operating Officer, said: "We are delighted that Alain Prost has accepted the role as our brand ambassador.
"He is the best-qualified personality for talking about the progress made by Renault in the last few years on quality, technological innovation and performance."