Di Grassi, who now drives for Audi in the World Endurance Championship, was named Rookie of the Year in 2013 after finishing third in his first Le Mans 24 Hour race.
The 29-year-old Brazilian, who had one season in Formula One driving for Virgin Racing in 2010, is a much in-demand test driver, currently working with Pirelli tyres.
He has also been a development driver for the new Formula E Championship for electric cars which starts later in the year.
Lucas said: "I am delighted to be named a Laureus Ambassador and would like to thank the members of the Laureus Academy for asking me. We all know how effective sport can be in tackling problems and bringing people together.
Double Formula One world champion and Laureus World Sports Academy Member Emerson Fittipaldi said: "On behalf of the Laureus Academy, I am delighted to welcome Lucas as a Laureus Ambassador. Motor racing is in your blood if you are a Brazilian, like Lucas and myself, and he is highly regarded in the sport. I know he will be a great asset to Laureus."