The one-two underscores Germany's continued strength in equestrian disciplines, one of its last strongholds in reliably delivering gold medals.
Making her 17-year-old mare Dalera dance with elevated passage trots and rhythmic flying changes to a medley of Edith Piaf hits, von Bredow-Werndl reached an overall score of 90.09%.
The Games were the last big stage for Trakehner warmblood Dalera, who will retire as one of the best dressage horses in Olympic history.
"She is such a cool dude, but I could feel, especially during her victory lap, how much she enjoys it," von Bredow-Werndl said of the horse.
"I don't know when I will have a horse like her again, or if."
Werth, who won silver in the last Olympics and on Saturday became Germany's most decorated Olympian, was second again, albeit on a new horse, 10-year-old mare Wendy.
Charlotte Fry won bronze, repeating the third place Britain achieved in Tokyo with Charlotte Dujardin, who was barred from this year's Games over a video that showed her whipping a horse's legs multiple times. Dujardin has said she made an error of judgment that was out of character.
Since her Tokyo debut, von Bredow-Werndl, has finished the four Olympic dressage contests she has taken part in with a gold medal, pocketing the two individual titles and being in the winning teams at the two Games.
Germany secured the razor-thin team win over Denmark and Britain on Saturday. German eventing rider Michael Jung won his fourth Olympic gold medal on Monday.
Asked how she felt riding in a packed Versailles arena against the backdrop of the world-famous chateau, Bredow-Werndl said: "This is the most incredible arena, the most incredible dancefloor in this world and I am overwhelmed and extremely grateful."
Bredow-Werndl, 38 and a mother of two, lives on a horse farm close to the Bavarian Alps with her extended family, including her parents, who also had high-level sports careers, and her brother, Benjamin Werndl, a leading dressage rider.
Dinja van Liere, riding Hermes, was fourth while Denmark's Cathrine Laudrup-Dufour - seen as one of the hottest contenders for the final after getting the best marks in the qualification and team events - came in fifth.