Currently available in the US, it will be expanded to Facebook-owned Instagram and WhatsApp later.
It is not yet clear if Facebook Pay will launch in India as Facebook's plans in the country are focused around WhatsApp Pay as it has a massive WhatsApp user base in the country. However, it hasn't been introduced so far due to regulatory issues.
It is also not known if both Facebook Pay and WhatsApp Pay will be introduced in India.
According to the social networking giant, users do not need to download anything new Facebook Pay works seamlessly on the apps they use.
Mobile billing will also be a mode of payment on the platform, said the firm's payment terms.
"Getting started is quick and easy. Simply add your credit card, debit card, or PayPal, and you're good to go," the company said in its support page.
Eligible users can set up Facebook Pay by setting it up for use across all Facebook apps individually. They can go to Settings > Facebook Pay, on the Facebook app or website, then add a payment method.
It is pertinent to note that Facebook Pay is also not connected to its proposed cryptocurrency wallet Libra.
The company will not charge a fee from the users for sending and receiving money via Messenger app.
Facebook may, however, subject users to fees from third parties for reversal charges or insufficient funds if attempted payments are rejected.
Users who are under 18 will not be able to use the peer-to-peer (P2P) payments service on Messenger.
P2P is also not to be used for business, commercial, or merchant transactions. The company will discontinue payment services if it notices such prohibited transactions.
( With inputs from IANS )