A total of 41,472 migrants crossed the Channel in small boats in 2025 – almost 5,000 more than the previous year.
Home Office figures showed a 13% rise on the 36,566 total in 2024.
It was the highest number since 2022, when nearly 46,000 migrants crossed.
The government says it has already removed 50,000 people who were in the UK illegally and is working more closely with the French government.
Figures from the Home Office then showed 737 people arrived on 13 December, and more than 600 more in the following four days.
A total of 803 people arrived in 13 boats on 21 December, a record for a single day in December.
The last arrivals of 2025 were on 22 December, when 17 people were brought ashore at Dover.
A Home Office spokesperson said: “The number of small boat crossings are shameful and the British people deserve better.
“This government is taking action. We have removed almost 50,000 people who were here illegally, and our historic deal with the French means those who arrive on small boats are now being sent back.”