The 24 year-old France international joins on an initial loan with the option to buy.
“I am really excited to be signing for West Ham United,” said Todibo, who enjoyed loan spells with German club Schalke 04 and Portuguese side Benfica as a youngster. “It is a dream come true to play in the Premier League, the best league in the world.
“This is an amazing opportunity for me, at a Club with huge ambition, who want to really make progress under the new Head Coach.
“It feels like the right time to be coming to West Ham, in the heart of London, with an amazing, passionate fan-base. I’m so excited to pull on the West Ham shirt, and play at the London Stadium in the Premier League.”
Hammers technical director Tim Steidten also stated: “This is another significant signing for the Football Club and shows the attraction of West Ham for top players in Europe.
“It’s no secret that Jean-Clair is a player we’ve been tracking for some time, so we’re delighted to have got this signing over the line ahead of the start of the new season.
“He’s got proven pedigree in European football, especially in France, where he has shone in recent years, showing all of his qualities as one of the finest ball-playing centre-halves in Ligue 1.
“There was huge interest from across Europe for his signature this summer, and we’re once again indebted to the Board for backing us to bring in a player who is approaching the peak years of his career.
“I’m sure the West Ham fans are excited about Jean-Clair’s arrival, and we can’t wait to see him playing in a West Ham shirt.”