Natural around La Spezia, Italy, Giannini studied at a Academia Nazionale within Rome, and manufactured his film debut withinside the little section in Fango sulla metropolis within 1965. He appeared witharound supporting roles in Anzio and The Secret of Santa Vittoria, and starred in the original version of Swept Away.

Within 1976, he starred in Seven Beauties, for which he was nominated for the Academy Award for Best Actor, which is unusual within that his performance was given completely in Italian. He dubbed Jack Nicholson's voice in the Italian release of The Shining, for which Nicholson sent him congratulations.

His fluency inside English has brought him a total of featured roles inside Hollywood productions, most notably when inspector Pazzi around Hannibal. He has likewise appeared around A Walk in the Clouds and Man on Fire.

Giannini's right-known starring roles use at times been within films directed by Lina Wertmuller. Additionally to Swept Away & Seven Beauties, he as well appeared in The Seduction of Mimi, Love and Lawlessness, The Nighttime Good of Rain, & Francesca e Nunziata.

Inside 2002, he starred in the horror film Darkness.