Veteran hooker Mealamu is on extended leave and will not return until mid-March as he recovers from the rigours of a hectic 2012 season with the All Blacks and the Blues, who finished last in the New Zealand conference.
"I think it's an incredibly important time for Ali Williams," Blues head coach John Kirwan said in a statement.
"I think he's got a heck of a lot to offer this franchise, he's a world class lock with the ability to lead a team and I'm extremely enthusiastic and positive about this decision."
Kirwan said the 31-year-old Williams' recent history of injuries was taken into consideration before selecting the 77-test veteran for the job.
"He's had a bad run of injuries but I think he's ready for this because he's had a bad run and some people think he's finished. I don't believe that and neither does he," the coach said after the side's first official day of pre-season training.
Williams himself was no less excited.
"I am a hugely passionate man when it comes to the Blues and it is a great honour to lead the team next year," Williams said.
"It's an extremely tough job and I respect that. There have been many great leaders of this team before me and my job along with the team is to strengthen the strong traditions that the Blues have."
The Blues kick off their 2013 Super Rugby campaign against the Hurricanes in a Feb. 23 match in Auckland.
- Sports & Recreation
- Employment & Career
- Ali Williams
- John Kirwan