Now he will be tasked with adding to a new-look Milan squad under Gennaro Gattuso that will set its sights on the Champions League next season after an extended period away from European competition.
A surprise signing, a young talent: AC Milan have signed Alen Halilovic to build on the desire to create a stronger and younger team," the Rossoneri signalled in a statement released on their official website.
"Alen has great potential, though his career has not yet flourished. He arrives in Serie A fully motivated, ready for that boost following his spell in La Liga.
"Left-footed, 169cm tall and 69 kilos, he is a creative and technical player with playmaking ability in the tight space, capable of operating throughout the midfield as no.10, winger or holding midfielder offering, therefore, a range of tactical solutions to Rino Gattuso.
"The young Croatian tends to move in from the right threatening in the middle with abilities to break through the line. Welcome, Alen!"
His arrival at San Siro follows that of goalkeeper Pepe Reina and left-back Ivan Strinic, both on free transfers.