The Canadian pair triumphed 14-21, 22-20, 15-12 against Switzerland's Tanja Hueberli and Nina Brunner, rallying after a poor start at the spectacular venue in front of the Eiffel Tower.
Switzerland were on the brink of victory in the second set but their opponents dug deep to level the match and force a tense decider.
The ecstatic Canadians fell to the sand, hugging and laughing, before running into the crowd for high-fives.
Humana-Paredes said she was "a runner when I celebrate", adding that the team still had more to give in Friday's gold medal match.
In the first men's semi-final, Germany's Nils Ehlers and Clemens Wickler beat Tokyo 2020 gold medallists Anders Mol and Christian Soerum of Norway 21-13, 17-21, 15-13.
Germany's Ehlers, who stands at 6 feet 11 inches (2.11 metres), used his height and reach to great effect as Germany took the first set.
But to the delight of their fans, some wearing Viking helmets, the Norwegian pair battled back to square the match.
After a tight decider, a dramatic review challenge over a net fault ruled in favour of the German pair.
The winners collapsed on the sand, with the stands shaking to the sound of thunderous stamping.
Later Thursday, Qatari pair Cherif Younousse and Ahmed Tijan will take on Sweden's David Ahman and Jonatan Hellvig in the second men's semi-final.
Brazilians Ana Patricia Silva Ramos and Eduarda Santos Lisboa will face Tokyo 2020 silver medallists Taliqua Clancy and Mariafe Artacho del Solar from Australia in the other women's semi-final.