"The great crises of our time require all of us to do more," Gates said, referring to the Covid-19 pandemic, the war in Ukraine and climate change, among others.
He added that the compounding effects of crises, which include surging inflation, had increased the need to invest more in the foundation's core focus areas of health, education, gender equality and poverty alleviation.
The donation brings the 22-year-old organization's endowment to about $70 billion, which includes a grant of $3.1 billion from Warren Buffett last month.