Barros studied in New York in The Reads Strasberg Theater Institute to study acting; she later transferred over to Actor's Studio Film & T.V School where she studied film and television, and in the Broadway Dance Center, tap and jazz. After living a couple of years in New York, Barros moved back to Mexico City and enrolled in an acting school to brush-up her acting skills.
After working in Mexican television for several years, Barros was given her first starring role in the 2003 telenovela Mariana de la Noche where she essayed the title character with Jorge Salinas as her leading man. In 2006, Barros co-starred in the Mexican telenovela remake of 1986's El Camino Secreto now titled La Verdad Oculta opposite Eduardo Yáñez. Both versions were written by Jose Rendon. In 2008/2009, she appeared with Alejandro Camacho in Alma de Hierro. She teamed up with Camacho and Jones once again in 2010's critically acclaimed Para Volver a Amar by Gómez Fernández and Giselle González, where she portrayed Bárbara Mantilla, the suffering, yet flighty and carefree wife of an abusive alcoholic. For her efforts, Barros won the award for Best Actress in a Co-Starring Role given by Revista TV y Novelas in their annual Premios gala on March 6, 2011.
Also in 2010, Alejandra Barros co-starred with Eugenio Derbez in the romantic comedy No Eres Tu, Soy Yo which went on to become one of the highest-grossing films in Mexican cinema history.
Alejandra Barros acted in Carlos Moreno Laguillo's telenovela: Quiero Amarte.