They have been granted three-month visas with no right to work and no recourse to public funds, the PA news agency has been told.
The Home Office said the move was part of “critical first steps” under the scheme after the removal of four people from Britain.
The agreement, which came into force last month, is aimed at deporting migrants who have crossed the English Channel in exchange for those who apply in France and are approved to come to the UK.
The Government has said the newly established legal route for those entering the country includes rigorous documentation as well as eligibility and security checks. They will then be able to claim asylum in Britain.
A spokesperson for the Home Office said: “This is a clear message to people-smuggling gangs that illegal entry into the UK will not be tolerated.
“We will continue to detain and remove those who arrive by small boat.”
Imran Hussain, director of external affairs at the charity Refugee Council, said: “This is a really welcome step. No family should ever have to risk their lives in a flimsy boat just to reach safety.
“By opening up safe and legal routes, we not only give children and parents the chance to rebuild their lives with dignity, but we take power away from the smugglers who profit from people’s desperation.”
Ministers hope the scheme will act as a deterrent to those considering making the dangerous journey across the Channel as the Government grapples with soaring numbers of arrivals.
A total of 32,188 people have arrived in Britain by small boat so far in 2025, with more than 1,000 in a single day last Friday, after returns to Paris commenced under the deal.
The Government intends to increase the number of people being sent back under the pilot agreement, which runs initially until June next year.