The software is designed to provide a way for users to communicate as an alternative to email and other intranet systems.
The firm says information posted within the service is kept "secure, confidential and completely separate" from personal Facebook profiles.
The move poses a challenge to LinkedIn.
The work-focused social network recently announced its own plan to release a new app to help co-workers share information.
Facebook's move also threatens other established collaboration tools targeted at businesses including Yammer - which Microsoft bought for $1.2bn (?788,000) in 2012 - Jive and MangoApps.Email overload The service is designed to help avoid important messages being missed because of email overload
Facebook already has about 1.4 billion people using its platform at least once a month, but it is currently blocked in some workplaces.
The Menlo Park, California-based firm suggested one advantage it had over rival work communication tools was that people were already familiar with the way it worked, meaning firms could save on training costs.
Many companies are keen to adopt such software because of complaints that a deluge of messages has made email a poor tool to keep in touch with.
"Facebook at Work is a separate experience that gives employees the ability to connect and collaborate efficiently using Facebook tools - many that they're likely already using such as News Feed, Groups, messages and events," the social network said in a statement.
"The information shared among employees is only accessible to people in the company."
A spokeswoman added: "Internally at Facebook we've been using our product for years, and we're now looking forward to the feedback from our pilot partners to create the best possible experience."
One industry watcher said the move was no surprise.
"If you look how popular things like Yammer have already been, that shows that there is definitely an appetite for a business skew of Facebook itself," said Chris Green, principal technology analyst at Davies Murphy Group Europe.
For now, the Facebook at Work app is free-to-use, but limited to an unnamed group of companies that will trial its use.
At this stage the work version will not feature adverts, nor will it gather data about its users that could be sold on to third parties.
"Businesses would be concerned if it became ad-supported with information shared for context-driven marketing posts - that would be a no-no for a lot of companies on data protection grounds," commented Mr Green.
"Companies would probably be happier paying a subscription fee - as is the case with Yammer - and having an ad-free closed environment that they can keep total data control over."
Facebook responded: "It's too early discuss future plans around ads or monetisation."