Jaidi was part of the Championship's meanest defence while at Birmingham
Southampton boss Alan Pardew has signed experienced centre-half Radhi Jaidi, subject to work permit clearance.
The Tunisia international was out of contract this summer after being released by Birmingham City.
Jaidi has penned a two-year deal at St Marys which will begin when the authorities give him the green light.
Meanwhile Senegal striker Papa Waigo N'Diaye has joined on loan from Serie A side Fiorentina until the end of the season, also subject to a work permit.
Former Birmingham and Bolton man Jaidi said of his transfer: "The first thing is that Southampton is a big club and I have known that ever since I came to England,"
The giant defender joined Birmingham City for £2m in 2006 as they looked to get back into the Premier League at the first attempt.
Having previously played in the Premier League with Bolton Wanderers, he joined the midlands outfit in the Championship and played 38 games during his first season at St Andrew's as Steve Bruce's side won automatic promotion.
I think I can add strength and experience to the team, and that's what I will bring to help us reach out targets
Jaidi played for just one team before moving to England, Esperance Sportive de Tunis, where he began in 1993.
Jaidi has firmly established himself on the international scene and has played for his country in the last two World Cups, scoring in Tunsia's 2-2 draw against Saudi Arabia in 2006.
He was also a key part of side the lifted the 2004 African Cup of Nations, which was hosted by the Tunisians themselves.
A powerful and experienced defender, at almost 6'4'', he will also bring additional height and strength to the Saints backline.
Jaidi added: "As soon as I was given the opportunity to come here I accepted because I know this club has a big infrastructure.
"I think I can add strength and experience to the team, and that's what I will bring to help us reach out targets."
N'Diaye, 25, has played his entire career in Italy with Verona, A.C. Cesena, Genoa and Fiorentina.
He was picked as part of the Senegal squad for the 2008 Africa Cup of Nations tournament in Ghana.
"We wanted another creative player and he comes highly recommended," said Pardew.
"He's a quick, creative forward player who will help us score more goals and I can't wait to see him in a Saints shirt."
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