In the Before Times, said Rebecca Rittenberg, a 28-year-old who works in advertising sales for Google in New York, one of her favorite parts about going to the office was “showing up in a funky, cool professional outfit.”

A smart pair of pants, colorful or patterned blouses, blazers, skirts, dresses, heeled boots and designer sneakers were all part of her wardrobe, which she used to express her personality and keep up with her stylish ad world colleagues.

Now, after eight months of working from home, and with Google saying workers won’t have to return in person until next summer at the earliest, a big swath of that apparel has been donated and replaced. Ms. Rittenberg’s new definition of “work clothes” includes cashmere cardigans and joggers, headbands, and other cozy garments that fall somewhere in the “healthy in-between” of pajamas and blazers.

“I looked at my stuff I used to wear to the office all the time and thought, ‘When am I ever going to touch this again?’” she said. “Our mind-sets have shifted a bit with this pandemic and the fact that we’ve all been working from home for so long. Once we are back in the office, which I do think will happen, it just seems like a pretty extreme jump to go back to wearing a blazer and pencil skirt and heels again.”

As many professional women have found themselves in an extended period of remote work, their notions of work wear have transformed, shaking up businesses that have sought to outfit them for the office. American office attire was already facing the effects of “casualization” — even Goldman Sachs loosened its dress code last year — but as the pandemic drags on, the shift is accelerating and may stick around for good.

Bloomingdale’s has watched customers increasingly seek out cashmere, flat shoes, pants with elastic waistbands and other comfy apparel, while brands like Theory have rushed to add more casual clothing to their lines, said Denise Magid, an executive vice president at Bloomingdale’s who oversees ready-to-wear apparel.

“Regardless of when people go back to the office, I think people have grown comfortable with what they’re wearing,” Ms. Magid said. “I just can’t see people giving away the feeling of comfort.”

The retail landscape is changing with the new needs of the remote worker. Bankruptcies this year included Brooks Brothers and the owner of Ann Taylor and Loft. Rent the Runway closed all of its stores and removed its unlimited subscription option. In Gap Inc.’s latest quarter, net sales soared 15 percent at Old Navy and 35 percent at Athleta while plummeting 34 percent at Banana Republic.

Gap named a new head of Banana Republic last week and said on an earnings call that the brand had been “working hard to update its product assortment” for an era of remote work, favoring more casual clothes over tailored garments and suiting.

Professional women have long been a lucrative market. Retailers see them as customers who tend to have money to spend and are willing to pay for apparel that will help them feel confident in the workplace, fit into busy lifestyles or offer up the right look for a “desk to dinner” sort of day. The attire is often dry-clean only, stiffer and more structured than weekend clothes, and modest in neckline and hemline. Many of those products — and how they are marketed — have now changed.

Last fall, Banana Republic’s site and social media featured colorful heels and models wearing “quintessential Banana Republic with a modern twist — think cozy cable knits and Italian corduroy, double-breasted plaid blazers and moleskin jackets.” This season, its site includes looks for virtual interviews and a “work leisure” section, with soft ponte leggings, turtleneck sweater dresses, cheetah-print socks and “coatigans.”

Some women appear to be clearing out office attire from their closets through donations and resales. The RealReal said consignments of work dresses more than doubled between Aug. 1 and Oct. 15 compared with the same period last year, exceeding significant jumps in consignments of cocktail dresses and evening dresses. On Poshmark, listings of women’s blazers and suit jackets from July to Sept. 30 jumped 30 percent from a year earlier, while listings of women’s pencil skirts rose 32 percent.

Jackie Temkin, 33, had already started selling many of her more formal Washington, D.C., office clothes on Poshmark after graduating from business school in 2018 and establishing a design studio in Charlottesville, Va. But she said demand for such apparel had seemed to dry up since March.

“I feel that a lot of employers have learned you really can get a lot of stuff done at home and workplace norms from before are no longer applicable,” Ms. Temkin said. She added that her work wardrobe was already radically different from how she recalled her mother dressing for her job as a lawyer.

“She had dress suits and skirt suits and things like that, and that was their uniform every day,” Ms. Temkin said. She recalled her mother once using fake tanner on her legs in the summer to make it look as though she were wearing pantyhose. “It’s just such a huge shift,” she said.

M.M.LaFleur, a seller of stylish women’s workplace apparel that was founded in 2011, has worked to recover from the hit it has taken this year. The brand has cut back on suiting for the spring and leaned more heavily into the “power casual” category, which it introduced several years ago.

“It was actually inspired by our San Francisco tech customers, who were saying, ‘I can’t wear dresses or a suit to work because then people think I’m interviewing, but I’m also not going to wear a hoodie and sweatpants like the engineers because that is so not me,’” said Sarah LeFleur, the brand’s founder and chief executive. “That style has become more mainstream now, so a lot of what we have been doing is really designing to that woman.”

It includes cashmere sweaters, a “jardigan” jacket and “better than jean” pants. Ms. LeFleur said that while sales of Zoom-friendly tops had initially outpaced bottoms during the pandemic, there was a sudden uptick in pants in June.

She could relate. “After 100 days of being in sweatpants, I needed to feel like I was getting out of bed,” she said, adding that customers have gravitated to pants that look tailored but feel as comfortable as sweatpants.

The company has also rebranded some of its wares. Its crisp-looking “Colby pants,” once marketed in an “Origami Suiting” collection as wrinkle resistant and easy to fold for business trips, were renamed “Colby joggers” online, with new emphasis on their casual appeal and elastic waistband. Sales soared sevenfold. The brand was helped because it already carried machine-washable work wear, a product of Ms. LeFleur’s belief that dry cleaning is “a sexist industry” based on its prices for men’s and women’s clothing.

Kathryn Minshew, the 35-year-old founder of the Muse, a site for job seekers in their 20s and 30s, said she had become far less tolerant of portions of her wardrobe that she once wore to the office, including trousers and certain dresses.

“I didn’t have very much clothing that was incredibly uncomfortable, but I had a lot of clothing that was normal work wear uncomfortable,” she said. “It was a little bit structured, a little bit tight, it pulls a little bit when you move in certain ways. A lot of work dresses and work tops for women that are fitted, they’re fine, but they’re not the most comfortable things.”

She anticipated that “many women will keep a part of their closet for powerhouse outfits and special occasions.” But, she added, “I do believe it will get smaller over time the longer that the pandemic goes on and therefore the more that we collectively get used to this type of living and working.”

Ultimately, Ms. Minshew said, any longer-term shifts could help ease the pressure women feel to present themselves a certain way in the workplace.

Indeed, Ms. Rittenberg from Google said she realized that she was dressing for herself more than ever rather than for clients, her team or the office at large, which has been refreshing.

“The pandemic equals so much craze in our life,” she said. It stands to reason, she said, that people are “trying to make their clothes as comfortable, fuzzy and warm as possible so we don’t have an added layer of structure and chaos that we didn’t ask for.”