Semenya, a former world 800m champion, and Hogan, who was fifth in his specialist discipline at the 2013 global showpiece in Moscow, made use of an extended qualifying deadline set by Athletics SA to accommodate athletes battling with injuries or illness.
They were the only two athletes to be added to the provisional 29-member national team announced last month.
Aside from Semenya, the squad also includes former World Championships medallists Johan Cronje, LJ van Zyl, Khotso Mokoena and Sunette Viljoen.
SA team for the IAAF World Championships (August 22-30):
Men: Henricho Bruintjies (100m), Akani Simbine (100m/200m), Anaso Jobodwana (100m/200m), Wayde van Niekerk (400m), Berend Koekemoer (400m), Rynardt van Rensburg (800m), Johan Cronje (1 500m), Stephen Mokoka (10 000m), Antonio Alkana (110m hurdles), LJ van Zyl (400m hurdles), Cornel Fredericks (400m hurdles), Zarck Visser (long jump), Ruswahl Samaai (long jump), Khotso Mokoena (long jump/triple jump), Orazio Cremona (shot put), Jaco Engelbrecht (shot put), Victor Hogan (discus throw), Rocco van Rooyen (javelin throw), Willem Coertzen (decathlon), Lebogang Shange (20km walk), Marc Mundell (50km walk), Benedict Moeng (marathon), Desmond Mokgobu (marathon), Lucas Jani (marathon), Sibusiso Nzima (marathon)
Women: Carina Horn (100m), Justine Palframan (200m/400m), Caster Semenya (800m), Wenda Nel (400m hurdles), Sunette Viljoen (javelin throw), Tanith Maxwell (marathon)