On 31 January 2006, he moved to Premier League team West Bromwich Albion on loan for the rest of the season with the option to make it permanent.
Manager Bryan Robson, who signed him on the recommendation of former Uruguay international striker Daniel Fonseca, hoped that Martínez would be as good as fellow West Brom centre-back Curtis Davies.
[2] Martínez made his West Brom debut on 11 February 2006 in a 6–1 loss at Fulham, coming on at half time as a substitute for Thomas Gaardsøe; he received a yellow card in the game, and afterwards, manager Robson called the entire defence "shocking".
[9] In August 2009, Martínez returned to Defensor after cancelling his Valenciennes contract a year early, as he did not feature in the plans of manager Philippe Montanier.
In February 2019, he made a return to European football leagues for the first time in nearly a decade, as the 36-year-old signed for AD Ceuta FC in the Spanish fourth-tier Tercera División.
Accompanying Diego Lugano in central defence, the team drew 1–1 in the final against Iran in Hong Kong before winning 4–2 in a penalty shootout.