The organization said the estimate margin has a range in which the total deaths could be as low as 13.3 million or as high as 16.6 million.
According to the WHO's existing figures, there have been 6.2 million COVID-19-related deaths reported worldwide.
Messages of gratitude are seen in New York City's Times Square early during the coronavirus pandemic on April 19, 2020. File Photo by John Angelillo/UPI
The new estimate accounts for people who died as a direct result of the coronavirus disease, or indirectly because hospital systems were overwhelmed with cases of the virus.
"These sobering data not only point to the impact of the pandemic but also to the need for all countries to invest in more resilient health systems that can sustain essential health services during crises, including stronger health information systems," WHO Director General Dr. Tedros Adhanom Ghebreyesus said in a statement.
"WHO is committed to working with all countries to strengthen their health information systems to generate better data for better decisions and better outcomes."
The organization said that most of the extra deaths -- 84% -- were concentrated in Southeast Asia, Europe and the Americas and affected men (57%) more than women (43%). The difference was also higher among older adults.