"The Messenger team's mission is to make Messenger the best place to communicate with all the people and businesses in the world," Facebook head of messaging products Dave Marcus said in an online post.
"I'm happy to report that we've made a good step in that direction, and toward the end of 2015, we crossed the milestone of 800 million people using Messenger every month."
He maintained that while the number was impressive, it was still "early days" for Messenger.
Improvements to the smartphone messaging application last year included ramping up speed, making it easier to send photos, adding video calling, letting businesses use it for customer service and adding the ability to send money to friends.
Facebook also began testing on weaving its "M" digital virtual assistant into Messenger. The test of enhancing Messenger with artificial intelligence is "going well," according to Marcus.
Facebook last month announced an alliance with Uber that lets people in the United States summon cars from the ride-sharing service using the Messenger application.
The partnership was a major move for both California firms, further expanding Facebook's stand-alone messaging service beyond simply communicating and putting Uber in touch with a huge user base.
Uber was described as the first partner in the launch of "transportation on Messenger," leaving the door open to add Uber rivals as options for users of the smartphone messaging service.
"You can expect us to keep trying new things, too," Marcus said.
"There will be more innovative developments to come from Messenger this year."
Connecting with businesses
Plans for this year include doing more to enable businesses and services to connect with people using Messenger, according to Facebook.
Messenger is working with players in e-commerce, travel, aviation and other industries to test modes of interacting with people on the service, Marcus told AFP in an interview here.
He said that people appreciate being able to easily interact with companies in conversational manners on Messenger.
Messenger is also keen to play a role in e-commerce globally, considering it a natural fit for the service but noting that international payments systems face "complications."
The ability of one person to send money to another using Messenger, however, is being developed country-by-country and will take "a little time," according to Marcus.
Facebook holds another messaging application, WhatsApp, which had more than 900 million users as of late last year.
Marcus said that Messenger and WhatsApp operate "fairly independently."