He began playing guitar at the age of seven and composing his first songs three years later. The young musician started attending management classes after moving from the neighborhood of Pueblo Nuevo to Moratalaz.
At the age of 16, Alejandro Sánchez recorded Los Chulos Son Pa' Cuidarlos. However, his official debut, called Viviendo Deprisa, came in 1991 after signing up with Warner Music. Si Tú Me Miras followed in 1993, featuring contributions from Nacho Mañó, Chris Cameron and Paco de Lucía. His third album, aptly titled 3, was recorded in Venice, Italy, and produced by Miguel Angel Arenas and Emanuele Ruffinengo.

1997's Más and 2000's El Alma Al Aire, the Spanish singer/songwriter achieved international top-selling status.

He also appeared in the film clip for The Corrs' English translation of their duet, "Una Noche" ("One Night") as Andrea's love interest. The video is included in The Corrs' DVD version of Best of The Corrs. In return, The Corrs sang "The Hardest Day" with him and "Una noche" for the Spanish and Latin American edition from the 2001 Corrs' greatest hits album.

In 2001, he became the first Spanish artist to record an Unplugged for MTV.

In 2003, he recorded the album No Es Lo Mismo, which won five 2004 Latin Grammy Awards. It won Record Of The Year, Album Of The Year, Song Of The Year, and Best Engineered Album with Mick Guzauski, Pepo Sherman, and Rafa Sardina as engineers.
In 2005, Sanz worked with Shakira in the hit single "La Tortura".

On September 25, 2006, Sanz released the song "A La Primera Persona". It was the first single from his new album El Tren de los Momentos which was ultimately released in November 7, 2006. The album also produced another hit duet with Shakira titled Te lo Agradezco, Pero No.

On October 2, 2007, Alejandro Sanz launched his own fragrance called "Siete" (Seven).

A Korean rendition of Sanz's "Y Si Fuera Ella" is featured on K-pop boyband SHINee's first album of 2008.

Sanz is a critic of Venezuelan president Hugo Chavez.

Discografía

2004: No Es Lo Mismo: Edición Especial Gira
2004: grandes éxitos 91_04
2006: Viviendo Deprisa (Edición 2006 with extra content)
2006: Si tú me miras (Edición 2006 with extra content)
2006: 3 (Edición 2006 with extra content)
2006: más (Edición 2006 with extra content)
2006: El alma al aire (Edición 2006 with extra content)
2006: No Es Lo Mismo (Edición 2006 with extra content)
2006: El Tren De Los Momentos
2007: El Tren De Los Momentos: Edición Especial
2007: El Tren De Los Momentos: En Vivo Desde Buenos Aires