"Conchita is a Spanish tennis legend and it is fitting that those who have given a lot to our sport have a chance to continue helping the team," RFET president Jose Luis Escanuela said on the federation's website (www.rfet.es) on Saturday.
Martinez, now 40, beat Martina Navratilova in the 1994 Wimbledon singles final. She reached the finals of the Australian Open in 1998 and the French Open two years later and rose to number two in the world rankings.
As a player, she helped Spain to win five Fed Cup titles and since her retirement has worked as a coach, a television pundit and tournament organiser.
Sanchez-Vicario stepped down after Spain lost their World Group first-round tie to Russia in last year's Fed Cup. They play their World Group II match at home to Ukraine next month.