In July 2019, Elle Woodworth was raising three children with her husband in Fort Myers, Fla. when she had an idea to generate income that would change the course of their lives.

Not that she had such high expectations at first: “I was only trying to solve a problem,” she said.

The townhouse they were living in felt cramped, and her husband was working up to 60 hours a week as a restaurant manager. “One day I was cleaning out the garage with the kids and saw these folding chairs my husband had picked up on the side of the road a few months prior,” said Ms. Woodworth, 36. “I thought, ‘Why don’t I post a listing on Facebook Marketplace and try to make some extra money?’”

She listed the set for $35 and the chairs sold that day. Three years later, Ms. Woodworth is the co-founder of Elle Woodworthy, a secondhand furniture business that brings in six figures a year — enough for the couple to move into a larger home and allow her husband to quit his job all within months of their first sale.

Perusing the likes of estate sales and flea markets to buy furniture secondhand is nothing new, but when the pandemic forced many to stay home and inadvertently assess their surroundings, they also spent much more time online. Flipping old furniture by completely revamping or even just cleaning it up drew, for some, online followings and profits, all while sidestepping supply chain issues.

“I think the pandemic is the biggest driving force behind the furniture flipping craze on social media,” said Trisha Sprouse, 44, a furniture flipper who lives in Jacksonville, Fla. “People shared their projects, which in turn inspired others, and eventually it blew up into something bigger. ”

According to Lisa Revelli, a spokesperson at Meta, furniture listings on Facebook Marketplace in America have increased more than 40 percent so far in 2022 when compared to the same time last year. Similarly, the number of users following #furnitureflip on Instagram grew by 29 percent within that period. On TikTok, that hashtag has spurred more than 18,000 videos with nearly 225 million views in the U.S. since the beginning of this year.

“When I started doing this, it cost $400 to $500 to take out an ad for a month in the Yellow Pages,” said Eric Lewis, 44, the owner of BC Modern in Milwaukee who has been restoring and selling furniture for nearly 20 years.

“It used to be that older folks were interested in my pieces because that’s what they grew up with, but with TikTok and Instagram, the audience is skewing younger,” he said. “Nothing has really changed about the process of getting furniture and fixing it up, but the demand has changed.”

Clinton Avery Tharp, 37, lives in Oklahoma City and has been flipping furniture for more than a decade to supplement his career as a musician.

“I’ve always been the type of person who changes something about a room five times a year,” he said. When the pandemic started, he downloaded TikTok to stave off boredom and saw others starring in bite-sized performances of their modifications. “The first thing I thought was that I could be funnier,” he added.

Mr. Tharp put together a video showing himself taking the skirt off a white sofa using a deadpan yet encouraging tone. The post went viral, and now he routinely gets recognized at thrift stores thanks to having close to a million TikTok followers. “It helps that my character is a bit dry, so I can say ‘Hi!’ and then ‘Bye!’ and they’re satisfied,” Mr. Tharp said.

Like Mr. Tharp, Christina Clericuzio, 25, who works in sales for a tech company in Trumbull, Conn., downloaded TikTok in 2020 thinking it would keep her occupied while quarantining with her parents. When she came across a bevy of furniture projects, she thought she could try it for herself — particularly because her family had inventory collecting dust in their basement.

“I taught myself by watching YouTube videos,” she said. Ms. Clericuzio usually begins sanding down a piece on Thursday night, and then uploads a completed tutorial on Sunday. Tens of thousands of her Instagram and TikTok followers wait for them to appear, and then she sells the items through Facebook Marketplace.

“It looks easy when you’re watching the videos, but a lot goes into it,” she said. “And, of course, it takes longer if I screw something up.”

To find free or low-cost furniture like dressers, couches, night stands and dining tables, flippers spend countless hours primarily scrolling through Facebook Marketplace. (“The stuff people need for their first apartments,” Mr. Tharp said.) They seek out estate sales, garage sales, thrift stores and flea markets — sometimes crossing state lines — sifting through mountains of other people’s memories hoping others can see a future in owning them.

It’s best if the contenders are made of solid wood and don’t require too many hours of labor, whether that means adding fresh paint and hardware, or a new stain and varnish.

“I’m looking for quality, condition and style,” Mr. Lewis said. “Most people want something with character.”

“If I see a furniture item that can look like something from Anthropologie, for instance, I’ll do that,” Ms. Clericuzio said. “If we’re being honest, so many people can’t afford to spend thousands of dollars on furniture and those pieces aren’t going to be as durable as something built in the past. So it’s fun to show people that they can have these things for less when they D.I.Y.”

Ms. Sprouse keeps most of what she upcycles, but others try to turn a profit. A good month is when Mr. Tharp sells up to 40 pieces to in-person and online customers; Ms. Woodworth sells up to 50 pieces with help from wholesalers; and Mr. Lewis sells up to 200 pieces to visitors to his store.

At the same time, Ms. Clericuzio and Mr. Tharp have gotten some criticism about their handiwork. “Most of what’s said is positive, but a recurring negative comment that I get is that by shopping at thrift stores I’m taking away from poor people,” Mr. Tharp said. “There are furniture banks in every state and ways to get these things for free. Not to mention, so much of what’s donated ends up in a landfill.”

After the success of selling her folding chairs on Facebook Marketplace, Ms. Woodworth continued to use the platform to reach her local community. Then she discovered that Etsy and Chairish could entice customers from throughout the country.

“That’s when our business really skyrocketed,” she said. She no longer flips furniture in the sense of painting or adding new features to it. Like Mr. Lewis, she describes “flipping” as finding a well-built item, cleaning it up, and promoting its enduring craftsmanship.

Now that Ms. Woodworth and her husband have established their business together, they’re focusing on having several hundred pieces of furniture available for purchase one day. “This all started with the simple goal of wanting to buy our own home, spend more time together and have more flexibility,” she said. “Flipping has made that possible for us.”