The General Assembly proclaimed the day "to highlight the importance of the prevention of, preparedness for and partnerships against epidemics," said the UN in a statement.
The adoption came days after hundreds of world leaders took part in a virtual special session of the international body in response to COVID-19.
They demanded urgent action to guarantee equitable distribution of coronavirus vaccines during their addresses Thursday and Friday.
Vietnam's UN Ambassador Dang Dinh Quy introduced the text, saying COVID‑19 is not the first pandemic, nor will it be the last.
"The pandemic caught us off guard, but it also has served as a wake‑up call for improving our preparedness," he said in the statement.
Worldwide, the death toll from COVID-19 has surpassed 1.5 million since the virus was first detected in Wuhan, China in December last year.
The number of infections totals more than 67.5 million and recoveries over 43 million, according to the latest figures from US-based Johns Hopkins University.
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