The 35-year-old has not played since being sacked by West Bromwich Albion last month for an alleged anti-semitic gesture, reports Xinhua.
“There is nothing to hide, it’s all agreed to. The documents are signed,” Atletico Mineiro’s president Alexandre Kalil told Radio Band News Sunday.
Anelka is expected to arrive at the Belo Horizonte club Tuesday.
Earlier, Kalil ended days of speculation by declaring on Twitter: “Anelka is a rooster” in reference to the club’s nickname.
Anelka will join Ronaldinho, and Brazil striker Jo as Atletico defend their Copa Libertadores title.
The Frenchman’s 19-year professional career has included spells at Paris Saint-Germain, Arsenal, Real Madrid, Liverpool, Chelsea and Manchester City.