Williams was born in [[Pamplona]] to Ghanaian parents who had fled to Spain 8eight years earlier as refugees of the [[First Liberian Civil War|Liberian Civil War]].<ref>{{cite news|url=https://en.as.com/en/2020/03/04/videos/1583335992_941432.html?autoplay=1?omnil=resrelart|title=Iñaki Williams explains how he got his name and why Bilbao means so much to him|newspaper=Diario AS|date=4 March 2020|access-date=21 January 2021}}</ref><ref>{{Cite web|url=https://footy-ghana.com/2020/06/spain-u17-coach-david-gordo-tips-bilbao-youngster-nico-williams-for-greatness/|title=Nico Williams: Spain U-17 coach tips Bilbao youngster for greatness|website=Footy Ghana|date=1 June 2020}}</ref> Nico's older brother, [[Iñaki Williams]], is also a footballer and a forward; he too was brought up at Athletic Bilbao having been born in Spain a short time after his parents arrived there.<ref>{{cite news|url=https://www.mundodeportivo.com/futbol/athletic-bilbao/20190210/46341074569/nico-williams-inaki-athletic-juveniles.html|title=El hermano de Iñaki Williams debuta con gol en el juvenil del Athletic|trans-title=Iñaki Williams's brother debuts with goal for Athletic youths|newspaper=Mundo Deportivo|first=Endika|last=Río|language=es|date=10 February 2019|access-date=14 February 2019}}</ref><ref>{{cite news|url=https://www.abc.es/deportes/futbol/abci-imparable-ascenso-nico-williams-athletic-202101310132_noticia.html|title=El imparable ascenso de Nico Williams en el Athletic|trans-title=The unstoppable rise of Nico Williams at Athletic|newspaper=[[ABC (newspaper)|ABC]]|first=Jorge|last=Abizanda|language=es|date=31 January 2021|access-date=25 February 2021}}</ref>
