Kipyegon, a triple world champion and the world record holder, is seeking to become the first woman to win three Olympic golds in the same track event. Poland's Anita Wlodarczyk achieved the feat in the hammer throw.
The Kenyan, who won silver in the 5,000m on Monday, has not lost over her preferred distance for three years and ran a controlled race, sitting in the pack running a slow pace until 500 to go before easing to the front and coming home comfortably first in 3:58.64.
Her biggest threat in Saturday's final is likely to come from Ethiopian duo Gudaf Tsegay, the world 10,000m champion, and world 1,500m silver medallist Diribe Welteji, who looked good in winning the second heat in 3:55.10.
In-form Jessica Hull will hope to win Australia's first medal in the event and Tokyo silver medallist Laura Muir is one of two Britons in the final alongside Georgia Hall.
A great atmosphere will be guaranteed by the rare presence of a home athlete in the final after Agathe Guillemot ran a French national record 3:56.69 to go through.
Birke Haylom, the 18-year-old Ethiopian who messed up her heat and had to come through the repechage, failed to make it.