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 after they sealed the win, hugging and laughing before running into the crowd for high-fives.
"I'm a runner (when I celebrate)," said Humana-Paredes. "It was an out-of-body experience. I think my body just had this huge release and I needed to get that energy out.
"I don't think we've played our best volleyball yet. I think it's somewhere inside and hopefully tomorrow we can bring it out."
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.
After the match a visibly emotional Ehlers said he had "goosebumps and tears in my eyes".
"I almost have no words. We can go for gold. It's incredible."
As dusk settled over Paris and the floodlights came on, the second women's semi-final started, with Brazilians Ana Patricia Silva Ramos and Eduarda Santos Lisboa taking on Tokyo 2020 silver medallists Taliqua Clancy and Mariafe Artacho del Solar from Australia.
Qatari pair Cherif Younousse and Ahmed Tijan will play Sweden's David Ahman and Jonatan Hellvig in the second men's semi-final.
