The pandemic has accelerated consumers' adoption of online shopping around the world. Investors holding e-commerce stocks in 2020 have been richly rewarded, but what will the coming year bring? Will the coronavirus vaccine take back those gains as we get "back to normal," or will the momentum continue?

Shopify (SHOP -1.16%), Square (SQ -0.42%), and MercadoLibre (MELI -0.81%) are three top e-commerce stocks that are well-positioned to have their best year ever in 2021. Let's find out why.

Shopify: Powering merchants' success

Shopify makes it easy for merchants to set up and run e-commerce stores, but its offerings go way beyond that. The company has built a massive ecosystem to support store owners and power their success.

A massive library of free content and access to thousands of professionals who can help is just the beginning. Last quarter, the company provided over $250 million in capital to merchants for funding growth initiatives. "Buy now, pay later" options for consumers have helped boost merchants' sales during a challenging economic environment. And Shopify's Fulfillment Network offers merchants easy access to an integrated fulfillment solution that's high quality and low cost.

What's even more exciting for investors is that Shopify's success is aligned with its merchants. Even though customers pay monthly subscription fees to use the Shopify platform, its merchant solutions segment is a larger portion of the top line. This segment is made up of services such as payments, fulfillment, capital, and shipping, which are charged as fees when a store makes a sale. Last quarter, merchant solutions revenue grew 132% year over year to $522 million, accounting for 68% of the top line.

Shopify's merchants are chalking up record results this holiday season, setting up the company for another record quarter and a solid 2021.

Mini shopping cart with ecommerce boxes inside on top of a laptop keyboard.

Image source: Getty Images.

Square: Helping brick-and-mortar retailers go virtual

At first blush, you might not put Square in a basket of e-commerce stocks, but that would be underestimating the breadth of its seller ecosystem. Over the past year, the company's online services have helped both existing sellers and those new to the platform. Square recently reported over 50% year-over-year growth in online gross payment volume. And in the third quarter, half of all new sellers to the platform signed up because of Square's online store capabilities.

Throughout this year, Square has made it a priority to support sellers and their moves online. Early in 2020, the company released new features for curbside pickup and delivery options, and it made these upgrades free. This has powered new highs in the online channel -- 25% of sellers' gross payment volume in the second quarter came from online sources, up from 14% the previous year. And online activity grew to an even larger percentage of the whole as in-person transactions declined 5% in the latest quarter. It's clear that sellers have embraced these capabilities and are using them to adapt their businesses to consumers' new shopping habits.

Sellers scrambled this year to build online stores, so it's not likely they will abandon this channel when things get "back to normal." This will enable sellers to reach more consumers than ever in the coming year

MercadoLibre: Facilitating commerce in Latin America

MercadoLibre, Latin America's leading e-commerce platform and fintech business has seen unprecedented growth this year. Last quarter, both of these segments put up triple-digit year-over-year revenue increases (in local currency). The company topped $1 billion in its quarterly top line for the first time ever. But what's even better is the number of customers, which has reached record levels in both segments.

For the marketplace, the platform saw a record 35 million unique buyers. In Brazil, its largest market, two million buyers made purchases on the platform for the first time. Even Chile and Colombia, two of its smallest markets, saw better than expected growth in the e-commerce marketplace. Fintech services also logged a new high of nearly 60 million unique payers in the quarter. Seven and a half million new payers joined in Brazil alone. As more consumers and payers discover the ease and convenience of these digital platforms, they will likely come back again and again.

The company continues to invest in its e-commerce and fintech capabilities to maintain its lead in the region. With record growth in new customers this year, 2021 looks even brighter for this market leader.

The bottom line for investors

With amazing e-commerce growth this year, these stocks are near all-time highs, but that shouldn't scare away investors with a long-term mindset. These quality businesses are looking to build on the new customers and momentum they've built up this year for an even better 2021.

But I'm not just pitching these stocks -- I'm a shareholder too. In fact, these three make up about one-third of my overall stock portfolio, so I'm making my own bet that over the next decade, this trio will continue to be solid market-beating investments.