Josefina’s older sister had moved to the capital of Chile, Santiago, and she invited Josefina to join her there. In Santiago, Josefina met Hugo. Alejandro was born there in 1972.

In August 1973, his family moved to Spain. The family settled in Madrid, living in a camping caravan. When Alejandro was six years old, they moved to a complex on the outskirts of the town of Paracuellos de Jarama (Madrid).

Between 1991 and 1994, Amenábar made three short films which in a very significant way influenced his first full-length films: La Cabeza, Himenóptero, and Luna.

In 1997 he made Abre Los Ojos, a science fiction movie that had notable success at international festivals such as Berlin and Tokyo. Impressed by the movie, Tom Cruise bought the rights to adapt and produce the film, starring in a remake, Vanilla Sky.

His third large film was The Others, a ghost story starring Nicole Kidman. It was very successful at an international level, especially in Spain, where it was the most viewed film that year. The Others was also very popular in the United States, where it was at the top of the box office for several weeks. The film premiered at the Venice Film Festival in 2001, won eight Goyas, including the Best Picture and Best Director, and was nominated for best European Film Movie.

In 2004 Amenábar released The Sea Inside, a real life-story about a quadriplegic Ramón Sampedro (played by Javier Bardem), which addressed issues such as euthanasia, abortion, or “the right to a dignified life.” The movie won 14 Goyas, including best movie and best director, and an Academy Award for Best Foreign Language Film in 2004.

In 2004, Amenábar came out as gay. On 18 July 2015, he married David Blanco. Amenábar was raised Catholic, but later became Agnostic and is now Atheist.

In 2008 Amenábar released his next film, called Mists of Time; however he later changed the name to Agora. The film starred big-name actors including Rachel Weisz and Max Minghella. Agora premiered on October 9, 2009, and with a budget of 50 million euros, it is the most expensive Spanish film in history.

After a hiatus of almost seven years, Amenábar returned in 2015 with the thriller Regression, starring Ethan Hawke and Emma Watson. The film had its world premiere at the San Sebastián International Film Festival in September 2015, where reviews were lukewarm.