Charles Loeser was born in New York in 1864, and studied Art History at Harvard University, graduating in 1886. Among his fellow students were Bernard Berenson, William Randolph Hearst and George Santayana. In 1888, Loeser settled in Florence, where he met and married the young German pianist Olga Lebert Kaufmann.

Their Florentine residence, Villa Torri Gattaia, housed Loeser's important collection of Italian Renaissance works of art, and soon became a favorite gathering place for intellectuals and art lovers from around the world. Music lovers were invited to the Villa to attend concerts held by the Lener String Quartet, with whom Olga Loeser often performed.

Loeser was also one of the first to recognize the genius of CÚzanne, and acquired a number of his paintings which he installed in the private rooms of the Villa.

Charles Loeser died during a visit to New York City in 1928 on the eve of his return to Florence. He is buried in the cemetery Agli Allori in Florence.