Fulham have paid an undisclosed fee to Norwegian club Aalesunds for Finland international Sakari Mattila.
The 26-year-old defensive midfielder has agreed a two-year contract with an option for a further 12 months.
"From day one when I heard about the interest, I was looking forward to this moment," he said.
Mattila, who has six caps, could make his debut in the club's opening game of the new Championship season at Cardiff City on Saturday.
He is Fulham's seventh summer signing following the arrival of fellow midfielders Tom Cairney, Jamie O'Hara and Ben Pringle, defenders Jazz Richards and Luke Garbutt, and goalkeeper Andy Lonergan.
Fulham Football Club statement
Fulham is delighted to confirm the signing of Sakari Mattila from Aalesunds FK on a two-year deal, with a Club option for a further 12 months, for an undisclosed fee.
The 26-year-old defensive midfielder began his career in his native Finland with HJK Helsinki, and made his professional debut with the club's reserve side, Klubi 04. He soon progressed to the senior side and was given his first top flight run out in April 2008.
He was on the move soon after, though, as he made the switch to Serie A after agreeing a deal with Udinese. During his time in Italy, he went on loan to Ascoli, before taking in a similar spell at Swiss outfit AC Bellinzona, for whom he later signed permanently.
Mattila returned to Helsinki on loan in August 2012, before rejoining them on a permanent deal just under a year later. In November 2013, it was announced that he had agreed to sign for Norwegian side Aalesunds on a three-year deal, and he was soon appointed captain.
He made the first of his appearances for the Finnish national side in March 2014, having previously represented his country for a variety of age groups.
Speaking to fulhamfc.com after putting pen to paper, Mattila said: "Of course I'm very delighted and happy to officially be a member of FFC. From day one when I heard about the interest I was looking forward to this moment, and now that it's official I'm really happy.
"I haven't been training with the team yet but the facilities and the atmosphere that you have here in the Training Ground is very special."