Beginning November, the Biden administration will lift travel restrictions on foreigners who have been fully vaccinated against the coronavirus, reopening the country to thousands of people, including those who were separated from family in the United States during the pandemic.

Foreign travelers will be required to show proof of vaccination before boarding and a negative coronavirus test within three days of arriving in the United States, according to Jeff Zients, the White House pandemic coordinator, on Monday.

For more than a year, the administration has prohibited foreigners from flying to the United States from a group of European countries, Iran, and China.

Unvaccinated Americans abroad who want to return home will have to pass stricter testing requirements. They will need to test negative for the coronavirus one day before traveling to the United States and show proof that they have purchased a test to take once they arrive, according to Mr. Zients. The Centers for Disease Control and Prevention will also issue an order soon directing airlines to collect travelers’ phone numbers and email addresses for a new contact-tracking system. Following their arrival, authorities will contact the travelers to see if they are experiencing any symptoms of the virus.

In the hopes of preventing disease spread, the Trump administration began implementing travel bans against foreign travelers in January 2020. The effort was largely futile. The previous administration’s muddled announcements about the restrictions also resulted in exoduses of American citizens, with crowded, chaotic airports with porous screenings.

Despite pleas from business leaders desperate for tourism profits, immigrant workers who traveled overseas to renew work visas to work in the United States only to be stranded, and citizens separated from their romantic partners abroad, Mr. Biden has maintained the restrictions against potential travelers from the European Union, Britain, India, and others.

The White House insisted that the restrictions were necessary, especially after the spread of the contagious Delta variant this summer fueled an increase in coronavirus cases and undermined Mr. Biden’s central theme of vaccinating Americans and bringing the pandemic under control.

Mr. Zients cited the administration’s pivot as the rate of vaccinations administered globally. The decision also comes on the eve of Prime Minister Boris Johnson’s visit, during which he was expected to press Mr. Biden to lift the ban. British officials had hoped the president would announce a relaxation of restrictions when he visited Cornwall, England, for the Group of Seven summit meeting in June, but were disappointed when he did not. Their anguish has only grown since then.

The relaxation of travel restrictions comes as the administration seeks to ease tensions with another ally, France, after the US kept Paris in the dark while secretly negotiating a deal with Australia to build nuclear submarines. Officials in the United Kingdom note that the United States has not imposed a similar ban on people from the Caribbean, which had a higher rate of infection than the United Kingdom, or Argentina, which had a lower percentage of its population vaccinated. In the United Kingdom, approximately 82 percent of people over the age of 16 have had two vaccinations.

Officials in the United Kingdom and several European Union countries allow fully vaccinated people from the United States to travel without quarantine, and they were irritated when the United States did not reciprocate.

According to European officials, the ban has kept families apart since early 2020, when the coronavirus was raging across Europe. The Delta variant has caused a third wave of infections in European countries. However, infection rates in several countries, including the United Kingdom, have begun to level off and even decline.

Giovanni Vincenti, a 42-year-old Italian professor living in Baltimore, reflected on the announcement, thinking about how his grandparents in Italy would finally get to meet his daughter, who was born last May.