Samuel Ogazi came third in Heat 3 of the men's semi-final in the Olympics.
The debutant ran a personal best time of 44.41s.
Great Britain's Matthew Hudson-Smith won the race in a time of 44.07s, while Michael Norman came in second in a time of 44.26s.
Ogazi is the first Nigerian athlete to qualify for the men's 400m final in 36 years.