Born in Madrid, Spain, Cantero graduated from Florida State University as an undergraduate and from Harvard Law School.

Prior to his appointment to the Florida Supreme Court, he was a shareholder in the Miami firm of Adorno & Yoss.

On July 10, 2002, Governor Jeb Bush appointed Cantero to the Florida Supreme Court.

Cantero is regarded as the first Florida Supreme Court Justice of Hispanic descent, contrasting with Rosemary Barkett who was the first Justice to meet the Census criteria for being Hispanic due to her birth in Mexico to Syrian parents and the fact that her first language was Spanish.

[1] On April 11, 2008, Cantero announced he would resign from the Florida Supreme Court, due to his family's desire to return to Miami, their hometown.