Diakite was released by Stars recently, after being deemed surplus to requirements together with his countryman Robert Sankara.
Also joining The Black Dolphins is Swaziland international Felix Badernhorst, who failed to land a deal with Kaizer Chiefs and Bloemfontein Celtic.
According to a source close to Vita, the club has also signed Botswana national team midfielder Onkabetse Makgantai, who attended trials with Baroka FC recently.
“The deal for Daouda is done. Felix [Badenhorst] from Swaziland and Onkebetse [Makgantai] have also signed,” said the source in Congo.