But many fans said it wasn't just her hair and make-up that looked different. Some described her as being 'unrecognizable', while more mean-spirited commentators said she looked 'Muppet-like', a reference to the children's show.
Dr Gary Motykie, a plastic surgeon-to-the-stars in Beverly Hills, California, told DailyMail.com that while Twain looked 'great' for her age, he saw several signs she may have had cosmetic enhancements.
He said that her lack of lines and 'more open' eyes suggested she may have had a brow lift, a procedure that involves making an incision behind the hairline to lift and tighten skin, smoothing wrinkles and reducing sagging.
He also suggested that her lack of wrinkles could be down to the use of Botox, and said her fuller face in earlier images suggested she had used filler.
He added that her dramatic costume made him suspect some work was done because celebrities can do this to 'distract from' cosmetic changes.
'It's an effective way to shift the focus and keep people speculating,' he added.
'In rcent years, Shania Twain has been known to use wigs to completely transform her look, allowing her to reinvent herself regularly.
'In the world of celebrity plastic surgery, we've also noticed that dramatic hairstyles are increasingly used to distract from changes that may have occurred due to going under the knife or receiving dermal fillers and Botox.'
Dr Adam Rubinstein, a plastic surgeon in Miami, Florida, told DailyMail.com that he suspected Shania may have had a blepharoplasty, also known as eyelid surgery.
'Shania has beautiful cheekbones, with an amazing jawline, she just has a great structure naturally and she is aging particularly well,' he said.
'But the one thing that I do see is that her eyes look really refreshed, the upper lids in particular.
'Her upper eyelids look a little bit fuller and heavier beforehand, but then when you look at the People's Choice awards they look a little bit more open and brighter.
He added: 'It may be make-up, but it does appear that because they look so refreshed that an upper eyelid lift — or blepharoplasty — is possible.'
Shania has denied having any plastic surgery, telling The Sun in May at the start of her third Las Vegas residency — Come on Over: 'Every month or day that I may notice another sag or another bit of cellulite, I want to know it's there.
'I want to be OK with it instead of thinking, I have to cover it up or not to look. I can't change it, and I don't plan on changing it superficially.
'I have to take myself on the stage without feeling like I have to cover myself up. I want to feel liberated.'
In January this year, she also denied the rumors while on the Hoda Kotb show, saying she loved her 'own skin'.
DailyMail.com contacted Shania's team for comment.
After she debuted the new look at the People's Choice awards, fans were quick to comment on social media with one saying: 'No way, she is not Shania'.
A second added, 'until I read this is she, I could not recognize her', and a third said, 'plastic surgery ruins what was a beautiful face'.
The surgeons also compared photos of Shania from 2008 to the late 2010s to suggest that she may have had filler.
Dr Motykie said: 'I think that what some people in her shoes, and a lot of people do, is when they start to age they want to try things that don't involve incisions and big surgeries.
'So they start playing with these things like injectable fillers and Botox to try and take out looseness in the skin without doing lifting or scars and, in many cases, they start overfilling.'
'They do a little bit, and a little bit more, and then that filler starts to take on water and they start looking poofy.'
Dr Rubinstein also suggested that her wrinkle-free appearance was likely aided by Botox, and he suggested she may be maintaining her lips with filler.
But he disagreed with suggestions that she had used filler in the rest of her face, saying: 'The kind of puffiness we see in filler is usually in specific places, and I am not seeing that with her, with her looking fuller generally.
'The puffier appearance may be down to weight gain instead.'
Dr Christopher Costa, who runs Platinum Plastic Surgery in Las Vegas, told DailyMail.com that he thought the initial shifts in her appearance were down to weight gain.
'I agree that her face has changed drastically over the last decade from a more full and round appearance to a much more sculpted and sharper look,' he said.
'However, my opinion is that the changes in her face may be more likely related to overall weight changes.'
In 2018, Shania underwent open-throat surgery to repair her vocal cords after their nerves were damaged by a Lyme disease infection.
The superstar said the illness left her unable to project her voice for seven years, and that she was 'petrified' about going under the knife to repair them.
She told the UK's Graham Norton show in 2023: 'I'm just grateful, honestly.
'I went a long time thinking I'd never be able to sing again or thinking I wouldn't be able to cheer at a sports game really loud.'
Shania is famous for her health and fitness routine, which has kept her body in tip-top shape for decades.
Revealing her diet in May this year, Shania said she is a vegetarian and only consumes fluids before her shows, such as spinach and blueberry shakes.
She also exercises three to five times per week, saying that she loves to play tennis — with the court being her gym.
Wouldn't we all like a nip and tuck if we could afford it? No one wants to look older or a bit worn out.
I think celebrities are in an even worse situation. They get ridiculed if they grow old naturally and if they appear to have had some work done to look younger, they can't win.
Shania was known for her beauty when she was younger and naturally she still wants to look her best now she is a bit older.
I think there's definitely double standards though as men don't seem to get the same scrutiny.
The Daily Mail is a noted rag over here too.
Honestly, what she did is pretty low-key and she's not unrecognizable at all. I especially see at the front of the eyebrows that it is pulled/smoothed. She sometimes has a strange wrinkle on the outside of her eyebrow. For me, her lips are natural, you can see that they are less plump and that she is playing on the makeup. She can still have expressions, her face is not frozen. Her smile will never get old and makes her look very good.
Shania has always pulled off different looks through make-up and different hairstyles. Even going back to when she was younger she could look very different from picture to picture. She employs the best make-up artists and hairstylists for a reason. I'm pretty sure plenty of the pictures are airbrushed to death too. People like to bitch and bash and jealousy often plays a big part. She probably has had a bit of work done, but fair play to her as she looks amazing for a woman who will be 60 next year. I still recognise her as Shania.