Spanish born Ghanaian international, Inaki Williams has signed a nine-year contract with Athletic Bilbao.
The 25-year-old has signed until 2028 and his new deal includes a 135m Euro (£125m) release clause.
"Hopefully great things can come because what I want to make this club bigger, if possible," he said.
"This, as you can see, is my house, and all I want, I have it here. The club has always bet on me, it has given me everything, I feel it is my home."
Williams, who made his senior debut for Athletic Bilbao in 2014, was linked with a move to Manchester United during the transfer window.
The contract is one of the longest ever handed to a player but does not surpass the 10-year agreement Real Betis handed Brazilian winger Denilson in 1998.
He opted to play for the Spanish national team instead of the Black Stars.