After beginning his football career at local club Vélez he had a very brief youth spell with neighbouring CD Málaga, where he was told he was not good enough for the sport, which prompted a return home.

[14] After just one year, Hierro returned to Europe to sign with Premier League side Bolton Wanderers[15] on the advice of his English teammate at Real Madrid Steve McManaman, and teaming up with another former player of that club, Iván Campo.

He scored once during his tenure, which came in a 3–2 loss at Norwich City in December 2004[16] and, even though hard-pressed by fans and manager Sam Allardyce to stay for a further campaign,[17] he announced his retirement from professional football on 10 May 2005.

He made his debut on 20 September 1989 – freshly signed by Madrid – in a 1–0 friendly victory over Poland in A Coruña,[19] and appeared for the nation in the 1990 (although only as a squad member), 1994, 1998 and 2002 FIFA World Cups, as well as UEFA Euro 1996 (where he missed a penalty as Spain crashed out to hosts England in a shootout) and 2000.

[20] One of Hierro's most important goals came during the 1994 World Cup qualification, as he headed the winner against Denmark that allowed ten-men Spain to qualify for the final tournament in the United States.

[32] He was appointed as the manager of Spain on 13 June 2018[33] after the sacking of Julen Lopetegui two days before their first match at the World Cup, following the latter's decision to join Real Madrid after the tournament.

[34] Two days later, he led the team to a 3–3 group stage draw against Portugal;[35] on 8 July, following a penalty shootout loss to hosts Russia in the round of 16, he stepped down from his post and also announced that he would not return to his role as sporting director.