Microsoft Teams' daily users figure is up to 44 million, having rocketed more than 37 per cent since last week, the vendor has said.
Microsoft said that the user count last Wednesday was 32 million, but 12 million have since been added.
The total figure is up from the 20 million reported in November last year.
In a statement, reported by CNBC, Microsoft VP Jared Spataro said that the COVID-19 outbreak will be "a turning point for the way people will work and learn".
"Our customers have certainly turned to Teams during this challenging time, and we've seen usage spikes in markets most impacted by COVID-19," he added.
Spataro also highlighted a number of businesses with over 100,000 users on Teams including Accenture, Continental AG, Ernst & Young, Pfizer and SAP.
Meanwhile, CEO Satya Nadella said that the data being gathered by Microsoft will help shape how modern workplaces will unfold.
"As organisations around the world are changing the way they work in response to this situation, we're going to learn a tremendous amount to transform how we work together," he said.
"There's going to be really a fundamental structural change in how we transcend some of these geographic boundaries."
Microsoft is in a head-to-head duel with Slack in the workplace collaboration space.
Slack reported a surge in demand last week, but its tentative outlook spooked investors and sent its share price plummeting.
It claimed to have 12 million daily users in October last year, according to Reuters, but did not offer an updated figure in its latest earnings announcement.
Microsoft last year reportedly banned its employees from using various forms of Slacks tech, claiming its security was insufficient.
Boss of Microsoft partner claims virus will fundamentally reshape investment decisions
NETconnection acquired for LAN capabilities
Vendor's DaaS offering had previously only been available in the US
Comms firm reports revenue decline and profits rise
Comms firm goes private in £627m deal
'Symantec abandoning large segments of the market' - CrowdStrike CEO says partners are looking for alternative vendors
CrowdStrike sales rocket in Q4
Intel says its on-time delivery rate is at over 90 per cent
Teams' daily users increase by 12 million in a week
Hackers posing as coronavirus charitable causes