Alonso was first noticed internationally in the 1959 film, Nel segno di Roma (Sheba and the Gladiator), which starred Anita Ekberg and Georges Marchal. Owing to a particularly erotic dance number, her picture and name became more prominent on the movie’s publicity posters than either of the two leads, much to Ekberg’s dismay.

In 1960, while making Morgan il pirata, Alonso met and married Aldo Pomilia, a production manager and producer. After making together Quattro notti con Alba (Desert War) in 1962, they had one son, Aldino Pomilia, and she retired for a while.

After the death of her husband in 1986, Alonso moved to the city of Siena in Tuscany, Italy. She retired from film and started a cat-breeding business, as well as a four-star hotel.

Chelo Alonso died on February 20, 2019, at the age of 85.