Méndez was born January 26, 1955 in León, Guanajuato, Mexico. She began her career in 1972 when a very important newspaper from Mexico City "El Heraldo" launched her as "El Rostro" meaning "the face", she won this title; she also appeared in an uncredited role in a film named Vuelven los campeones justicieros also known in the USA as The Champion Five Return. By 1978, she was a well known superstar throughout México and the rest of Latin America thanks to her successful telenovelaViviana. This soap opera took Méndez directly around the world, among the most successful run of her series would be Spain, Italy and France. Méndez playing the underdog in the story with a strong charismatic character. The huge impact she followed with equally-successful, Colorina (1980). She enjoyed another success with Tu o Nadie (1985), and in 1988 she was cast in the dual role of Leonor de Santiago and Diana Salazar in the soap-opera El Extraño Retorno de Diana Salazar (1988), written by Carlos Olmos. She appeared in Amor de Nadie (1990), then in Marielena, where she portrayed a Cuban girl in exile. Marielena (1992) is probably her most successful telenovela has ever made and the most sold of all her telenovelas.
Other soap operas include: Señora Tentacion (1994) Tres Veces Sofía (1998) and Golpe Bajo (2000).
In the music realm Méndez would record her first platinum album in 1975 alongside composer Juan Gabriel. The album, Siempre Estoy Pensando En Ti ("Always Thinking About You"), brought her huge success in the field.She recorded as many as five albums with Gabriel, this earned her recognition and credibility as a singer, and not only that but her albums were certified gold and platinum.
In 2011, Lucía starred in Mexico the telenovela Esperanza del Corazón ("Hoping Heart"), with Fernando Allende and the Mexican Broadway star Bianca Marroquín. Also in 2011, she was inducted into the Paseo de las Luminarias (Plaza of the Stars) for her work as a recording artist and in television