A lay ceremony will be held Saturday in front of the city's Gothic cathedral for the writer and actor, one of the leading figures in 20th century farce and political theatre, who died on Thursday aged 90.
Behind the coffin stood an easel featuring a photograph of a smiling Fo, brush in hand, while painting materials rested on a stool nearby in tribute to the provocative playwright, who studied fine arts and architecture in Milan
before turning to the theatre.
His son Jacopo and his wife and children were present at the Piccolo Teatro Strehler to share memories of the Italian master.
Fo was "a 360-degrees artist, he was an extraordinary innovator in the theatre world and linguistically as well," 27-year old history student Vincenzo Mirigliano told AFP, after placing a flower near the coffin.
"But he was also a great painter, creating works (...) with extraordinary colours," he added, saying Fo's genius lay in his ability to mix humour with moments of profound reflection.
Adalberto da Pieve, 80, who came from Milan's outskirts to say goodbye to the mime, stand-up comic, historian and political commentator, said "he was such an ironic person, we will miss him".
"Even the sky is crying today," added his wife Angela Sansoterra, 73, as dark rain clouds broke over the northern Italian city.
Fo, who was married to the actress and activist Franca Rame, won the Nobel prize for literature in 1997 and told Swedish Academy the award also belonged to his wife and life-long collaborator, who died in 2013.
He was best known for his works "Accidental Death of an Anarchist" and "Can't Pay, Won't Pay".