Sandra was born in Argentina, South America. She began her career in the modeling industry representing her hometown of Rosario in the Punte del Este beauty pageant. Winning the grand prize of a modeling contract with Rochas Perfume, Vidal was on her way to Paris. By age 17, Sandra was one of the top models on the European circuit, traveling from Madrid to Paris to Milan.
By age 20, she was a featured guest on numerous television shows in Argentina. Sandra was discovered on the sidelines of the runway at Argentina's most celebrated fashion event. The host of the fashion show asked her to join him as a co-host of his regular series program, El Mundo de Arte Gamaz. Vidal went on to host her own show Hacerte Cargo, where she became a huge hit with teenage viewers. Sandra also wrote economic articles for the show and received acclaim for her in-depth coverage and intelligent reporting.
Vidal began studying acting with renowned Argentine directors Alberto Ure, Rodolfo Vias and Flores Yunguerman. On the side, she continued to study economics as well as piano and dance. On a family trip to Miami, Vidal found a new agent, a new acting coach and a new contract with the Telemundo network, where she went on to star as "Elena Sanchez," the blonde in the telenovela Angeles, the Spanish version of Charlie's Angels.