Yego started off with 78.88m on his first attempt before making a wrong throw on the second attempt. He then made amends on the final throw to go slightly above the qualifying mark with 83.60m.
Yego was competing in Group B, which was won by Trinidad and Tobacco's Keshorn Walcott with a season best throw of 88.68m. Germany's Johannes Vetter was second with 85.96m ahead of Japanese Royhei Arai, who registered 84.16m.
Other qualifiers in the group were -Peter Frydrych (Cze) 84.16m, Vitezslav Vesely (Cze) 82.85 and Aritti Ruuskanen (Finland) 82.20m.
Germany's Julian Webber won Group 'A' with a throw of 84.46 with Jakub Vadlejch coming (Cze) second on 83.27 and Dmytro Kosynskyy (Ukraine) taking third place with 83.23m. Germany's Thomas Rohler (80.36m) and Australia's Joshua Robinson (80.84m) closed the top five places.
In an interview, Yego admitted that the competition will be tight but promised to give it his best shot as he seeks to add the Olympic title to his world crown.
The final will be held on Saturday at the Olympic Stadium.