Virtually unbeaten on the world circuit, Garnbret has been the face of sport climbing for years with eight World Championship titles and a gold from Tokyo 2020, where the sport made its Olympic debut.
The packed stands at the sun-filled Le Bourget venue exploded into cheers and applause when the defending Olympic champion was called onto the stage as "the one and only".
She casually topped the first of the four boulders on her first attempt. Hardly breaking a sweat, Garnbret flashed a smile as she grabbed the last hold with both hands.
The second wall was even easier, seeing her 'flash' the boulder for another 'super score' of 25 points in less than a minute out of the allotted five.
"The first two problems went smooth," she said.
Asked whether she felt any pressure as the undeniable favourite to retain her title, Garnbret said she was used to being in that position but that the Olympics were special.
"This is not some World Championship or World Cup. This is the Olympics. So you need to be 100% focused, you need to be ready, you need to have a good day and you need to have like a little bit of luck."
In the boulder discipline, athletes have a time limit to negotiate four walls and earn points on the highest-scoring holds they manage. In the lead discipline, athletes aim to climb a 15-metre wall as high as possible in a single attempt.
The top eight scorers for the combined boulder and lead stages advance to the final.
Garnbret, the only woman to top all four boulders, earned a total of 99.6 points and a huge surplus going into the lead semi-finals on Thursday.
France's Oriane Bertone placed second with 84.5 points and American Brooke Raboutou was third with 83.7 points.
