The 32-year-old ex Leicester City and Preston centre back has signed a short term deal until January.
Richard Money’s side need all the help they can get with the club bottom of the Vanarama National League.
The centre-half was a team-mate of Brazilian great Kaka at Orland City, but his next assignment is to keep his new club in the league.
St Ledger told the club’s website: “I’m pleased to be back playing football and I’m grateful for the opportunity to join Solihull, especially being from the area.
“I’ve not played a lot of football recently so it will be good for me to get some game time, but I want to help try and get the team up the table – that’s the main aim.
“I hope my experience will help. We need to win games and start winning them quickly. We all want to try and keep Solihull in the National League, we don’t want to drop down.
“I’m looking forward to the challenge, the games are going to benefit me and hopefully I can help Solihull get back up the table.”
In their last outing, Money’s team went down 4-0 to AFC Fylde having beaten Eastleigh in their previous outing.