The 23-year-old defender joins the Tunisian side on a free transfer after parting ways with the Urban Warriors at the end of last season.
The Ghanaian defender joined Ajax on a two-year deal in 2015, but failed to cement a regular place in the team, and his contract was not renewed by the Urban Warriors when it expired at the end of June.
Lartey, who is said to have signed a three-year deal, becomes the second player to sign for Club Africain this week after the Tunisian giants acquired the services of Congolese striker Fabrice N’Guessi Ondama.
The 29-year-old striker signed a two-year deal with Club Africain.
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