Sevilla said on Monday they had exercised their option to buy on-loan Spain attacker Suso from AC Milan.
The Spanish club said they had signed the 26-year-old on a five-year deal without revealing the transfer fee.
He has scored once in 19 games since joining the La Liga outfit in January.
Spanish media said the purchase option was around 21 million euros ($24 million) depending on whether Sevilla qualified for the Champions League, which they have.
Suso, who started at another Andalusian club Cadiz, had a spell at Liverpool, made more than 150 appearances over six seasons with Milan and has five international caps.