The Cottagers dropped down to the second tier of English football for the first time in 13 years by finishing four points adrift of safety in the table.
Amorebieta joined Fulham on a free transfer from Athletic Bilbao in April 2013.
"It's different football, it's a new team for me, a new experience," the Venezuelan told the club's official website. "It was not a good season because we went down and now we need to play in a different division and make sure we go up again."
Amorebieta scored one goal in 26 appearances for Fulham during the 2013-14 campaign.