Speaking outside his 10 Downing Street residence after a two-hour cabinet meeting, Cameron said the vote would be “one of the biggest decisions this country will face in our lifetimes”.
He argued that Britain would be “safer, stronger and better off” in the EU and said the concessions he negotiated with other EU leaders on Friday gave the country “the best of both worlds”.
“The choice goes to the kind of country we want to be,” he said, warning that proponents of a British exit from the EU were offering “a risk at a time of uncertainty, a leap in the dark”.
“Leaving Europe would threaten our economic and our national security,” he said.
The date of the referendum still has to be formalised by parliament, where Cameron will deliver a speech on Monday.