Sadler has signed a contract with Walsall until June 2012
Walsall have completed the signing of former Birmingham left-back Mat Sadler following his release by Watford.
The 26-year-old, who joined the Hornets from Blues for £750,000 in January 2008, has agreed a one-year deal at the Banks's Stadium.
Sadler spent last season on loan at Shrewsbury where he played in all 53 of the club's games.
Boss Dean Smith said: "I want players here who have hunger. Mat certainly fits into that category."
Smith added: "He played in every minute of last season for Shrewsbury and comes here with plenty of higher-level experience and a quality left foot."
The defender was a product of the St Andrew's youth system and his full debut for Birmingham came at 19.
Sadler went on to make 61 appearances before joining Watford, who he helped reach the Championship play-offs during his first season.
Since then he has slipped down the pecking order at Vicarage Road and has not played for them since Boxing Day 2008.
He spent the second half of the 2009-10 campaign on loan at Stockport.
He said: "I am looking forward to working here. Dean Smith's enthusiasm and determination to do well was clear to see from the off and it fits in with my own hopes and ambitions."