A Walmart store in Duarte, Calif. (Damian Dovarganes/AP)

After years of being outgunned in the online shopping realm by Amazon.com, retailing giant Walmart on Monday made a major play to boost its e-commerce firepower. The company said it has agreed to purchase start-up Jet.com for $3.3 billion, a move aimed at reaching a wider audience online.

The deal is one of Walmart’s most ambitious efforts yet to transform itself into a digital shopping juggernaut. Last year, the company pledged to spend about $2 billion over two years to enhance its online shopping capabilities with initiatives such as adding more fulfillment centers and expanding its grocery pickup program. Its cash-and-stock deal for Jet marks a significantly larger investment in building a digital-centric future.

Jet is an online general store that debuted last summer, making the lofty promise that it would deliver the best deals on the Internet through a unique approach to pricing. Prices at Jet are determined by the specific combination of items in your shopping basket, instead of on an item-by-item basis. Jet has indeed grown quickly, offering 12 million items for sale and averaging about 25,000 orders processed each day. However, it has hardly threatened to knock Amazon off its perch as the leader in online shopping, and it has been burning through cash rapidly as it spends on marketing and infrastructure.

Jet’s chief executive, Marc Lore, will continue to lead the brand he founded, and Walmart also plans to install him as head of its Walmart.com business. In putting Lore at the helm of its e-commerce division, Walmart is adding a one-time Amazon executive into a senior leadership position.

Data from NPD Group offers a window into why Jet may have been attractive to Walmart. The market research firm found that only one-fifth of Jet shoppers also shopped at Walmart.com in the last six months, meaning the big-box behemoth would gain access to new customers by bringing Jet under its wing. Plus, Jet customers are relatively wealthy: They are more likely than other online shoppers to have incomes of greater than $150,000 a year, NPD found. In an announcement of the deal, the companies touted the inroads Jet has made in creating a brand that has connected with millennials — a demographic that Walmart and virtually every other retailer is eager to court.

Walmart chief executive Doug McMillon told reporters during a conference call that one of things he liked about Jet was the extent to which customers have control over how much they pay. In Jet’s model, customers can get additional savings by choosing to waive the ability to return a purchase, paying with a certain type of card, and bundling orders together instead of buying items one at a time.

The companies said they plan to leverage each other’s technology solutions. Kirsten Newbold-Knipp, research director at Gartner, said the deal is “such a logical fit” when you consider how Jet’s back-end pricing technology could be entwined with Walmart’s supply chain capability.

Meanwhile, Jet could also benefit from Walmart’s robust network of stores and fulfillment centers, as well as the giant’s formidable buying power. The start-up, despite being one of the most well-funded young companies in history, has hit stumbling blocks as it attempted to crack the e-commerce market. Jet initially launched with a plan to be a membership-only retailer, one where all customers would pay $50 a year to access its rock-bottom prices. The idea was that profit would come exclusively from that fee. In theory, then, its item prices could be lower because it wouldn’t try to make a profit off them. And yet Jet was forced to drop the membership fee within months, likely a sign that the business model just didn’t get traction with shoppers. Late last year, the company reportedly received a much smaller valuation during a venture funding round than it had before.

In a press release, McMillon called the deal with Jet “another jolt of entrepreneurial spirit being injected into Walmart.” It also marks the latest twist in the unusual career arc of Lore. The Jet founder previously built Quidsi, a suite of shopping sites that included Diapers.com. After reportedly engaging in a punishing price war with Amazon, Quidsi was bought by Amazon in 2011 for more than $500 million. Lore stayed on at Amazon for a couple of years. (Jeffrey P. Bezos, chief executive of Amazon, owns The Washington Post.)

Lore has said the idea for Jet was grounded largely in his lessons from his Quidsi days. In particular, he came to believe that winning on price — not service — was the bedrock of a successful and durable e-commerce business. Jet was supposed to be different from Quidsi, though the two businesses now have striking parallels: Each was snapped up by a retailing behemoth looking to expand its empire.

Some analysts were skeptical that Jet and its promise of low prices could do much to help Walmart steal market share from Amazon. Dianne Inniss, a strategist at consultancy ThoughtWorks Retail, said in an e-mail that “Amazon has been moving away from price as a differentiator in favor of seamless convenience and deeper integration of its products and services into customers’ lives.”

Still, Walmart’s recent sales patterns underscore just how urgent it is for the retailer to build some momentum online. Global e-commerce sales grew just 12 percent last year, a slowdown from the 22 percent growth it recorded in 2014. Last year the Bentonville, Ark.-based chain rang up $13.7 billion online, compared to about $99 billion in sales for Amazon.

It’s worth noting that despite Amazon’s remarkable online ascent, Walmart still handily dominates the retailing scene overall. Walmart’s total revenue last year — which includes sales at its Sam’s Club chain — was $499.4 billion on a currency-adjusted basis. That is roughly five times times larger than Amazon’s sales. Its closest brick-and-mortar rival, Target, saw sales of $74 billion last year.  But Walmart is keenly aware that e-commerce growth is generally outpacing sales growth in brick-and-mortar stores, and so it is scrambling to adapt its business to that reality.

I hope that Walmart is not acquiring Jet because of the purple boxes and the discounts,” said Sucharita Mulpuru, an e-commerce analyst at Forrester Research. “Because that’s not the biggest asset. …What Walmart needs is that Amazon level of creativity and ingenuity. And that’s the question: Is that what these guys are going to be able to deliver for them?”

Walmart’s stock was down slightly in afternoon trading on Monday. The Wall Street Journal had reported last week that Walmart was poised to acquire Jet, so the news likely did not come as a surprise to investors. The companies said they expect the deal to close sometime this year.