This essentially means that Facebook hosting service will offer the same end-to-end encryption as WhatsApp currently provides to chats.
When Facebook acts as a hosting provider to a business, it will use the messages it processes on behalf of and at the instruction of the business.
The move, said Facebook, will make it easier to onboard to WhatsApp Business API, allow the businesses to respond to WhatsApp messages faster, keep their inventory up to date and sell products through chats.
"We're committed to providing people with a secure, transparent and privacy-protective way to communicate with businesses", it said in a statement late on Thursday.
Earlier, Facebook said it will finally start charging companies using WhatsApp for Business, as it expanded ways for its users to check out available products and make purchases right from a chat.
Some 50 million businesses and 175 million people message a WhatsApp Business account every day and this move will help WhatsApp continue building a business of its own while it provides and expands free end-to-end encrypted text, video and voice calling for more than 2 billion people.
According to the social network, every message sent on WhatsApp -- be it text, call, voice note or video -- uses the same industry leading Signal protocol that protects messages from before they're sent until they're delivered to the intended recipient.
But messaging a business is different than messaging a loved one.
Chats with businesses that use WhatsApp Messenger, WhatsApp Business app or that self-host the WhatsApp Business API to manage and store customer messages themselves are end-to-end encrypted.
"If a business chooses to use a third-party vendor to operate the WhatsApp Business API on their behalf, we do not consider that to be end-to-end encrypted since the business you are messaging has chosen to give a third-party vendor access to those messages," Cardozo said.
This will also be the case if that third-party vendor is Facebook.
While Facebook will not automatically use messages to inform the ads that a user sees, as is always the case, "businesses will be able to use chats they receive for their own marketing purposes, which may include advertising on Facebook".
Facebook CEO Mark Zuckerberg has time and again reiterated that all his apps -- WhatsApp, Messenger and Instagram -- will soon become a unified experience for billions of users.