Ince, who celebrated his 37th birthday on Monday, has put pen to paper on a one-year deal with the option of another year.
Saddlers boss Chris Hutchings told the club's official website: "I am delighted that Clayton has committed himself to the club.
"It means that we now have good competition in the goalkeeping department with Rene Gilmartin working hard during pre-season. This is a big boost as we prepare for the new season."
Trinidad and Tobago international Ince added: "I am happy with the news, the manager is happy with the news and hopefully the supporters will be happy too.
"Now we can concentrate on the season ahead because there are some big clubs in League One this year and it is going to be a real challenge."