She wowed critics and the public alike with her assured, elegant looks: a caped, scarlet column by Ralph Lauren at the Golden Globes; a princessy emerald-satin gown at the Baftas and - the piece de resistance - stunning ice-blue Prada pleats and a glittering Fred Leighton alice band for the Oscars.
"There was a campaign manufactured to make her an overnight sensation and it was done with fashion," says Bronwyn Cosgrave, journalist and author of Made for Each Other: Fashion and the Academy Awards.
"Yes, she got the Oscar, but the big payoff for Lupita was firstly the Miu Miu campaign, which gave her utter fashion credibility, and then the Lancome campaign."
Lupita Nyong'o in Ralph Lauren at the Golden Globes, on the red carpet at the 2014 Baftas and at last year's Oscars. Photos / Getty Images
The power players behind the stars are involved now more than ever.
"There really is this camp mentality in Hollywood," says Cosgrave. "It is much more organised than it was, say, 10 years ago; there's the manager, the agent, the business manager - these people have big teams behind them."
But at the heart of it all are the power stylists. Over the past decade, they have become stars with television shows and fashion lines, contracts with luxury brands and spin-off careers as celebrities in their own right. Their rise (and sometimes fall) is charted on The Hollywood Reporter's annual Power Stylist list. While the designers create the dresses, and ultimately an actress will decide what image she wishes to project and what she wants to wear, her stylist occupies a powerful position as the middleman.
The stakes get higher each year, too, with more awards shows and more media coverage than ever.
"The red carpet has become an event in itself, with channels like E! running three-hour-long programmes reporting on the clothes and interviewing the celebrities about their outfit," says InStyle editor Charlotte Moore.
"Because celebrities don't talk about their private life, fashion has become the fastest access to the biggest names. At the Globes last week, George Clooney and Amal went to speak to Giuliana Rancic from E! because they knew her questions would be purely fashion-based."
George and Amal Clooney on the red carpet at the 2015 Golden Globe Awards. Photo / Getty Images
For a fashion brand, dressing the right star - ideally, the coolest ingenue of the moment - can deliver priceless exposure.
"One image of the right celebrity in the right dress can go global in a matter of seconds," says Moore.
The Academy Awards are viewed by more than 40 million people in America alone, and many more globally, and then there are the endless column inches devoted to who wore what in the aftermath. It all makes Jennifer Lawrence's reported $15 million, three-year contract with Dior look rather reasonable - a deal signed hot on the heels of her remarkable rise during 2012 and 2013.
For stylists at next month's Oscars, the focus is now on the actresses who have been nominated for awards. You may well be the hottest stylist in town (and according to The Hollywood Reporter's 2014 list, this is Elizabeth Stewart, a former fashion editor who counts Cate Blanchett and Julia Roberts among her stellar clients), but if you aren't dressing any of the nominees, the stakes aren't nearly as high.
Jennifer Lawrence wearing Dior at the premiere of The Hunger Games: Mockingjay Part 1. Photo / Getty Images
Luxury brands will no doubt be eyeing up Emma Stone, who has been nominated for best supporting actress and, thanks to stylist Petra Flannery, wowed with her utterly chic Lanvin jumpsuit at the Golden Globes.
For some stylists, the pressure is doubled when they have two or even three actresses up for awards. Canadian Leslie Fremar, for example, who was formerly Anna Wintour's assistant at American Vogue, works with two of this year's nominees, Reese Witherspoon and Julianne Moore, who is widely tipped to win the best actress Oscar for her performance in Still Alice.
Emma Stone on the red carpet at the 2015 Golden Globe Awards. Photo / Getty Images
For once, there is a trio of British hopefuls, too. Rosamund Pike, whose stylist is Ryan Hastings, and Felicity Jones are both up for best actress. Dior - arguably one of the red carpet's biggest players - has been swift to court Jones and, along with stylist Karla Welch, dressed her in a deep jade gown for the Globes last week.
And then there's Keira Knightley, who, with stylist Leith Clark, has mastered a slightly boho red-carpet elegance with the help of brands such as Valentino and Chanel, with which she has a long-standing contract.
While the dominance of big brands, with their extensive budgets and manpower, has made the red carpet a blander place, there is still room for creativity - and the odd up-and-coming designer. Knightley, for one, has often championed young designers such as Erdem, Mary Katrantzou or Huishan Zhang.
"I think there is always room for up-and-coming designers," says UK Vogue's fashion features director, Sarah Harris.
"It's been so great to see relatively new London designers such as Emilia Wickstead dress Diane Kruger at this year's Golden Globes.
Keira Knightley's latest looks: At the Critcs' Choice Movie Awards, wearing Chanel at the Golden Globes. Keira on the red carpet at 2015 Bafta Tea Party and at the annual AFI awards. Photo / Getty Images
"For these designers, it's such important exposure - they don't advertise, they don't spend money on dressing celebrities; the red carpet is an incredibly important marketing tool for them. What is often hard is luring actresses away from bigger, safer brands and introducing them to these younger names. To that end, celebrity stylists are quite crucial with introducing them to what's new."
Ultimately, many actresses have to walk a tightrope between looking distinctive and of the moment (which could potentially attract more covetable roles) and sticking to classical, elegant, tried-and-tested Hollywood glamour.
"As much as I would like to see more variety on the red carpet, you can understand why actresses don't go off-piste in their choices," says Harris. "The press, together with the power of social media, now means that everyone can have a say on what is, and isn't, a winning look. A lot is at stake."
Cosgrave agrees: "If they turn up with one hair out of place, they get skewered and it could jeopardise a deal. A couple of years ago, I went to see Jessica Chastain on Broadway in The Heiress, and went backstage afterwards as I was with a friend of hers. He asked her what she was wearing to the Oscars.
She said: 'I am wearing what Middle America wants to see me in. I don't want to take any risks."'
