The 29-year old has signed a two-year deal with the Edinburgh club after leaving Colchester United at the end of last season and is now on his way to Scotland after spending his entire career in England so far.
"This is a new chapter in my career and I'm aiming to play my part in helping Hibernian to achieve success," Williams told Hibs' official website.
"I'm 29 now and I'm about to enter my peak years as a goalkeeper - I'm looking forward to experiencing that time in my career with Hibernian.
"This was probably the biggest decision of my career so far, but I believe it's the right choice and I'm excited about the challenge ahead."
Williams started with Manchester United back in 2002 and has since played for Coventry City, Chesterfield and Crewe Alexandra on loan before making a permanent move to Crewe in 2004. Since then he spent time with Carlisle United before moving to Colchester in 2009 where he was until this summer.