Montesano comes from a family involved in theatre, and he made his debut in 1966 in a show named Humor nero, alongside of Vittorio Metz. Later he became a very popular actor both on theatre and on television, thanks to his burlesque and brilliant style, and so during seventies he took part in several Italian comedies. He is probably best known for the role of Armando “Er Pomata” Pellicci in the cult movie Febbre da cavallo (1976), directed by Steno, but also for the role of Caleb, the good thief from Il ladrone (1980), directed by Pasquale Festa Campanile. Montesano won a David di Donatello as best new director for the movie A me mi piace (1985), in which he is both actor and director. His career continue from 1967 to 2010.
Montesano is married to Teresa Trisorio. He is the father of six children: from a previous marriage (to Tamara Moltrasio) he has two sons and one daughter (Tommaso, Oliver, Lavinia); another son (Mattia) was born to him by a longtime fiancée, Marina Spadaro; and two more (Enrico Michele, and Marco Valerio) he has by his present wife. He is an avid fan of the football team S.S. Lazio.