The 32-year-old signed a five-year contract with Mallorca on August 2007, following his release from Real Madrid.
In August 2008, Valero made a transfer to West Bromwich Albion, for a club record fee of €7 million (£4.7 million) with a four-year contract with the option of a further year in the club’s favour. Only 36 appearances were made for the Premier League side before he returned to Mallorca on loan in the 2009-10 season.
In July 2010, Villarreal agreed on a season-long loan of Valero, with the move to be made permanent at the end of the season. On 1 July 2011, Villarreal signed Valero on a permanent basis. In total, Valero completed 97 appearances for the Yellow Submarine, with 11 goals and 13 assists.
On 1 August 2012, Serie A side Fiorentina agreed with Villarreal for the transfer of Valero. He made an immediate impact at the Viola, scoring five league goals in 37 games in his first season and providing 11 assists as the team qualified to the Europa League.