Pupils in England have outperformed those in Scotland, Northern Ireland and Wales in international tests sat by hundreds of thousands of teenagers around the world.
England ranked above the other home nations in the Programme for International Student Assessment (Pisa) across all of reading, science and maths.
However the latest Pisa report, which is published every three years, also warned of a worldwide decline in teenagers' reading skills.
Teenagers were losing the skills that "matter most in the age of AI", such as being able to critically evaluate information from different sources, it said.
The share of "hasty readers", who rush through texts to give quick, incorrect answers, has almost doubled between 2018 and 2025. The report warned the fall was greatest in those from "relatively well off" families.
The Pisa tests, run by the Organisation for Economic Cooperation and Development (OECD), assess teenagers on their ability to solve problems, think critically and communicate, before asking them a wider range of questions about their education in a questionnaire.
Although the UK performed well overall, the rankings varied significantly again, with results showing England, where the curriculum is significantly different, pulling consistently ahead of Northern Ireland, Scotland and Wales.
England's schools minister, Georgia Gould, said the government wanted to "build on" the positive results and "go further so all young people leave school with strong literacy and numeracy".
The 2025 Pisa tests were taken by a sample of 760,000 15-year-olds in 91 countries. In the UK, where education differs between the home nations, 15,566 students took the tests in 515 schools.
In England, where it was recently announced that technical subjects would soon be available to students from age 14, Gould held up high-performing Estonia as an example of where "academic excellence can go hand in hand with high-quality vocational routes".
"Our reforms will build on England's strong academic foundations so future generations not only perform well, but feel connected to school and excited about where their education can take them," she added.
But Laura Trott, England's shadow education secretary, said the country's successes were down to previous reforms, and accused the new government of trying to "sabotage" them.
While Wales lags behind the rest of the UK overall, on science it is ahead of other European countries such as France, Spain and the Netherlands.
As the tests last year were taken by 15-year-olds, the results there largely reflect learning under an old curriculum, which has recently been changed.
Anna Brychan, Wales' minister for education and Welsh language, said plans were in place to support schools, adding that the results "highlight our need to improve standards of reading and maths, as a priority".
Scotland's education secretary, Mairi McAllan, said the results showed "real strengths in Scottish education, as well as areas we're already working to improve".
But Scottish Labour said results had "flatlined since 2022's historically poor results", while the Scottish Liberal Democrats said the education system under the SNP had "tumbled down the rankings, lagging behind England on every measure of performance".
Northern Ireland's education minister, Paul Givan, said pupils there had performed well by international standards, but that - like other countries - its education system was facing "significant challenges", adding that "there is much more work to do".
Overall, the Pisa tests provide the biggest global snapshot of education systems and an independent view of how teenagers are performing compared with their peers in other countries, so it is a relative measure.
