Later, he studied with painter Silvio Loffredo, professor of art at the Accademia in Florence, a pupil himself of the Austrian master Oskar Kokoschka. Loffredo encouraged him to develop his own style and vision. For inspiration, Sassone studied the works of the 19th century Italian impressionists, the Macchiaioli - Giovanni Fattori, Vito D'Ancona and Silvestro Lega. He began exhibiting his first works at this time. At the age of 25, he was selected to exhibit at Lo Sprone Cultural Center in Florence.

In November 1967, soon after the flood had devastated his city, Sassone traveled to the United States and settled in California. He later moved to Laguna Beach, a small seaside community, Mediterranean in geography and climate, with its own commitment to the arts. He became a regular exhibitor at the annual Festival of the Arts.

Throughout the seventies, he participated in a variety of exhibitions in the U.S. and abroad. Of his work then, the art critic for the Los Angeles Times, William Wilson, wrote: "Sassone is impressively gifted as a colorist and skilled in rendering reflections and color in light." (Wilson was reviewing a one-person show of his work at the Haggenmaker Galleries in Los Angeles, 11/14/75.)

In 1982 Marco Sassone was Knighted by president of Italy, Sandro Pertini, into the "Order to the Merit of the Italian Republic" and received a gold medal award from the Italian Academy of Arts, Literature and Science.

In the early 1980's Sassone moved his studio to San Francisco. In March 1988, the Los Angeles Municipal Art Gallery hosted the American Preview for his one-person exhibition to be held at the Bernheim-Jeune Gallery in Paris that April.

Art historian Donelson Hoopes published "Sassone", a monograph, in concurrence with the artist's exhibition at the Laguna Art Museum (November - December 1979). With prescience, Hoopes had observed: "Sassone's art has evolved from within, and such an organic, psychological and spiritual process may take his work along new and unforeseen paths." By the late eighties, Sassone had become increasingly concerned with social themes. He started working with the Inter Aid organization, donating paintings to raise money for the group's work with children in crisis. He also donated works to a non-profit group called Another Planet, based in Los Angeles, supporting that group's work with the homeless.

He began extensive - and personal - research on the homeless and painted a series of large canvasses and charcoal drawings portraying the life he observed on the streets. A number of these works have been exhibited at the Chicago International Art Exposition, the Basel Art Fair in Switzerland and the Jan Baum Gallery in Los Angeles, as well as in the exhibition "Body Politic" at the San Francisco Arts Commission Gallery and "Issue of Choice" at the Los Angeles Contemporary Exhibition (LACE).

In March of 1994, his exhibition "Home on the Streets" opened at the Museo ItaloAmericano in San Francisco later traveling to Los Angeles and Florence, Italy. Kenneth Baker, art critic for the San Francisco Chronicle wrote about his work: "There is true technical brilliance here…In the drawings, his technique seems to discover fresh descriptive possibilities each time out."

In 1997 Marco Sassone received a commission to create a 200 square foot mural in downtown San Francisco. The finished work comprised of five canvasses dedicated to the theme of Il Palio is installed in February of the following year.

In May 2001, the Museo ItaloAmericano in San Francisco inaugurated the exhibition, "Master and Pupil," works by Oskar Kokoschka, Silvio Loffredo, Marco Sassone. Author Peter Selz, writing in the catalogue about the artist's work, describes the link between the three artists: "A canvas like Chinese Reds (1990) in scarlet color relates to the chromatic scheme of his teacher's Angel of Death (1998), while alarming paintings like Marlboro Country (1990) with its human skulls spread in the foreground, or Coit Tower Night (1988) - a painting of deep blue water, a brown hill and a violent purple sky - all done with an agitated brush, elicit a fervent emotion, comparable to the sensations evoked by the canvases of Kokoschka himself."

The Palazzo Ducale Museum in Massa-Carrara, Italy presented his retrospective exhibition in March-April, 2002 with the publication of a catalogue written by Massimo Bertozzi. The exhibition was reviewed by La Nazione, Florence and La Repubblica, Rome.