More than 51,000 people have died and more than 208,000 have recovered, according to the university's figures.
The US accounts for the most cases; Italy the highest death toll.
The disease, Covid-19, first emerged in central China three months ago.
Though the tally kept by Johns Hopkins records one million confirmed cases, the actual number is thought to be much higher.
It took a month and a half for the first 100,000 cases to be registered. A million was reached after a doubling in cases over the past week.