"All British troops assigned to NATO's mission in Afghanistan are now returning home," Prime Minister Boris Johnson told parliament, praising what British forces had achieved while at the same time acknowledging the "perils" facing Afghanistan.
"For obvious reasons, I will not disclose the timetable of our departure, though I can tell the house (parliament) that most of our personnel have already left," Johnson said.
British forces were first deployed to Afghanistan in 2001 following the September 11 attacks on the United States and played a major role in combat operations until 2014.
A total of 457 British soldiers were killed in the country.
NATO, of which Britain is a member, said in April that its troops would begin withdrawing in co-ordination with a decision by President Joe Biden to pull U.S. troops out by September 11.