The duo are reportedly set to perform a version of Edith Piaf's "La Vie en Rose" as part of a glittering conclusion to the first-ever opening ceremony staged outside a stadium.
Instead, team delegations will set sail from the Austerlitz Bridge on a six-kilometre journey through the centre of Paris to a unique finale close to the Trocadero.
Dion, who is French-Canadian, teased her appearance in a post on X, writing: "Every time I return to Paris, I remember there's so much beauty and joy still to experience in the world. I love Paris, and I'm so happy to be back!"
The city has been preparing for the unique ceremony for months, and over recent days, the famous river has been increasingly hidden behind miles of chain-link fencing as part of a giant security operation.
Ticketed fans will have access to specially constructed stands on both sides of the river, while the ceremony's conclusion will be beamed around the city via 80 giant screens.
The concluding stages of the torch relay, which travelled through each of France's 64 territories before touching down in Paris in early July, are set to see rapper Snoop Dogg carry the flame through the suburb of Saint-Denis, home of the official games stadium, the Stade de France.
Olympic champions Tom Daley and Helen Glover will share flag-bearing duties at the head of the Team Great Britain contingent, marking the start of a games at which they hope to set a new post-war record of 70 medals from a single games.
The ceremony for the Olympics staged in Paris in 1924 took place at the Olympic Stadium in Colombes and welcomed 3,089 athletes, of whom only 135 were women. Dignitaries gave speeches and carrier pigeons were released into the air.
French President Emmanuel Macron has made the ambitious equivalent his project, telling reporters this week: "At the beginning, it seemed to be a crazy and not very serious idea.
"But we decided it was the right moment to deliver this crazy idea and make it real."
-- BERNAMA
