Netflix Inc. said it plans to shut down the last of its data centers by the end of the summer, which will make it one of the first big companies to run all of its information technology remotely, in what’s known as the public cloud.

“For our streaming business, we have been 100% cloud-based for customer facing systems for some time now, and are planning to completely retire our data centers later this summer,” the company said in an email to CIO Journal.

Corporate use of the public cloud, in which users share the resources of a service provider, is rising. But many companies still run sensitive software in their data centers or in private clouds, in which a company has dedicated cloud resources from a third-party or within its own premises. Many companies weave all of these assets together in what is known as a hybrid arrangement. While some smaller companies and startups are known to rely entirely on the public cloud, few large corporations do.

“A 100% cloud operation is going to be extremely rare for big established companies,” said Glenn O’Donnell, vice president and research director at Forrester Research. Forrester Research says many large companies are moving toward operating in the cloud, but are unable to migrate completely. Mainstream banks and insurance companies, for instance, still often use on-premises mainframe computers for financial transactions, according to Mr. O’Donnell. Legacy systems and applications are the most difficult to move to the cloud, he added.

The closing of Netflix’s last data center has been seven years in the making. Netflix said it experienced a major hardware failure in 2008, and began moving to AWS the following year, shifting its jobs page. It has been moving more platforms to AWS ever since, including its video player, iPhone related technology, discovery and search, and accounts pages. It shifted its Big Data platform in 2013 and billing and payments in 2014, the company said in a presentation at the end of last year.

Netflix said, with respect to IT infrastructure such as servers “we are fully reliant on Amazon Web Services.” It uses a variety of Web-based applications such as human resources software from Workday

“Cloud environments are ideal for horizontally scaling architectures. We don’t have to guess months ahead what our hardware, storage, and networking needs are going to be. We can programmatically access more of these resources from shared pools within AWS almost instantly,” Netflix said in a 2010 blog post, outlining the rationale for its new IT strategy.

About 12% of companies run IT operations entirely in the cloud, according to a recent survey of 1,500 IT professionals by BetterCloud, a company that makes management and security products. But nearly all of those companies are small or medium-sized businesses. By 2022, just slightly more than 20% of large enterprise companies are expected to operate entirely in the cloud.

Apart from its cloud vendors, Netflix also maintains a content delivery network through Internet service providers and other third parties to speed up the delivery of movies and web traffic between Netflix and its customers, according to a spokesperson. The company, which competes with Amazon in the video-streaming business, elected to keep control of its own content delivery network.

A CDN is a network that gets video to customer homes and caches it at local ISPs, so that a video doesn’t have to traverse the entire network every time a customer orders a movie or TV show.

Netflix has a small team of IT staffers who have been systematically moving the company's corporate systems to the cloud, according to Battery Ventures Technology Fellow Adrian Cockcroft, who until 2013 was Netflix's cloud architect. Netflix, founded eight years before Amazon launched its first cloud services, had "a lot of this stuff," Mr. Cockcroft said.

Netflix’s transition is a sign of the maturity of the cloud, as companies are now able to go all-in on a publicly shared computing platform. But, as Netflix's example shows, moving systems to cloud services can be a slow process. As the WSJ reported this month, even Amazon itself isn't entirely run on a public cloud.

Write to robert.mcmillan@wsj.com