Souare makes a return to the national side after a long layoff required to get back to full fitness after surviving a terrific accident in 2016.
Niasse, scorer of seven goals in 17 English Premier League matches this campaign, also return to Aliou Cisse's team after a long absence.
France-born Santy Ngom who plays for Nantes in the French top-flight has been given his maiden invitation to the national team set-up while Cardiff City’s Armand Traore returns to the squad since 2013.
Senegal will continue preparation for their second appearance in the quadrennial showpiece with games against Luxembourg and Croatia on May 31 and June 8 respectively.
Goalkeepers: Khadime Ndiaye, Alfred Gomis, Abdoulaye Diallo, S.Ndiaye.
Defenders: Kalidou Koulibaly, Pape Souare, Salif Sane, Moussa Wague, Fallou Diagne, Papiss Djilobodji, Lamine Gassama, Youssouf Sabaly, Armand Traore.
Midfielders: Assane Diousse, Idrissa Gueye, Badou Ndiaye, Cheikhou Kouyate, Alfred Ndiaye, Henri Saivet, Cheikh Ndoye.
Forwards: Santy Ngom, Mame Diouf, Moussa Konate, Oumar Niasse, Moussa Sow, Mbaye Niang, Diafra Sakho, Keita Balde, Sadio Mane, Ismaila Sarr.