In footage shared online, the British star can be seen breaking down in tears as they hug in The Colosseum at Caesars Palace, where Dion staged her residency for more than a decade.
After briefly talking while holding each other, Adele returned to the floor and told the audience: "Give it up for Ms Celine Dion".
An emotional Dion can be seen wiping her eyes with a tissue before she stood up and waved at the audience while Adele continued to sing her hit When We Were Young.
@ree.mcanthony_official #tiktok #adele #celinedion #emotional #crying #love #divas #legends #pourtoi #pourtoi #foryou ♬ son original - Tite Richmond Dagri
In another clip, Adele hails Dion as "one of my favourite people of all time" as she gestures to the singing superstar in the audience.
The Rolling In The Deep singer has been vocal about her love for Dion over the years, hailing her as "Queen Celine" after attending one of her performances in an Instagram post in 2018.
Alongside a photo of her wearing a Dion T-shirt, she added: "What a show, an absolute highlight of my life, thank you so much for the attention to your crowd and insane humour. Happy new year lady x"
Dion reciprocated the love at the time, sharing a photo to social media of her posing alongside Adele, who was wearing the singer's merchandise.
She wrote: "Wasn't able to do all my shows, but was thrilled that @Adele came to one of them.... I love her so much!! - Celine xx".
Adele returned to The Colosseum this weekend to continue her residency after taking a break to perform a series of shows in Munich in a purpose-built outdoor arena.
Weekends With Adele launched at Caesars Palace in Las Vegas in November 2022 and is due to conclude in November this year.
Her run of sell-out shows at the venue, which seats around 4000 people, has been a success but has also taken its toll.
In July, she announced she will take a "big break" from music after her run of upcoming shows.
Dion made a triumphant return to live singing in the summer to close the opening ceremony of the Paris Olympics amid her battle with stiff person syndrome (SPS).
She has spoken candidly about SPS, revealing her diagnosis in December 2022 after cancelling her Las Vegas residency in 2021 due to health concerns.
The condition is a rare autoimmune neurological disorder that most commonly causes muscle stiffness and painful spasms, according to the Johns Hopkins Medicine website.
In March 2003, Dion launched her first residency at The Colosseum, which played for 717 shows through to December 2007.
She returned to the venue for her second stint in March 2011 and played 424 shows before wrapping it up in June 2019.
With AAP.
