Deborah Carthy-Deu was born on January 5, 1966, in the Santurce district of San Juan to Ramón Carthy Sanchez and Vicky Sanz Deu, of Irish and Puerto Rican descent. Her mother directed an academy for ballet and modeling, Academia de Ballet y Modelaje Vicky Sanz, under the name of Vicky Sanz. Her father was a photography director. At age nine she started to take ballet classes at her mother's school. She was trained as a classical ballerina. She attended a Catholic elementary school and later enrolled in the ninth grade at Commonwealth High School. From age thirteen, she spent her summers in New York City taking dance classes. She later attended the University of Puerto Rico and pursued a major in drama. At thirteen, she also auditioned for Ballet Concierto and became part of the dance company and later a soloist.
Carthy-Deu graduated magna cum laude from the University of Puerto Rico and obtained the Theater Medal, awarded to the most distinguished graduate. She majored in theater arts and education. As an actress, she has worked both in theater and television and has earned the respect of critics for her participation, both in comedies and dramas. She owns a modeling and finishing school, known as Deborah Carthy Deu Estudio y Agencia de Modelos, in which she helps girls and women to develop social skills and self-esteem, as well as to start careers in modeling, the arts, television and participation in beauty pageants. Carthy-Deu has hosted several television shows in Puerto Rico, New York and Miami, working for both Univision and the Telemundo network on television programs such as Noche de Gala, with Eddie Miró, Desde Mi Pueblo, with Yoyo Boing and Tony Croatto, and La Buena Vida. She wrote a column for The San Juan Star. and had a fashion review on the entertainment magazine known Teve Guia until the publication closed. From 2007 to 2009, Carthy-Deu hosted a remake of Noche de Gala, produced by Paquito Cordero and broadcast by WIPR-TV. Since 2003, she has been a fashion contributor for WAPA's newscast Noticentro Al Amanecer. In December 2017, Carthy-Deu helped with the aftermath of Hurricane Maria by going door-to-door with the Federal Emergency Management Agency to help inspect residential damage.
