Just over four in five schools in Cornwall were rated good or outstanding at their last inspection, figures show.
The latest Ofsted data shows that 33 state schools in the area were graded outstanding, and 197 good as of December 31 – 83% of the 277 which had received an inspection by this point.
This was down from 85% in December 2019, before the coronavirus pandemic.
And it means the area's rate falls behind that across England, of 87%.
The proportion of schools rated good or outstanding nationally is the highest since comparable records began in 2010, but varied significantly between local authorities.
All 60 schools in the London borough of Camden were good or outstanding, compared to just 71% in Doncaster, in the North East.
Inspectors judge schools on categories including the quality of teaching, personal development and welfare, the effectiveness of the leadership and pupils' achievements.
Schools requiring improvement will be inspected again within 30 months, while those deemed good or outstanding will usually be reviewed again once every four years.
However, the figures show that just 2,400 schools in England were inspected between 2019-20 and 2021-22 as a result of the pandemic – fewer than would be rated in a typical school year.
The Association of School and College Leaders said this was a temporary issue, but warned that the real problem is the inspection system itself.
Geoff Barton, general secretary of the ASCL, said: “Schools in disadvantaged communities are more likely to receive negative ratings than those in affluent areas because it is often harder in these areas to recruit the range of staff needed to support pupils who may face significant challenges in their own lives."
He said it is a "vicious circle" where negative Ofsted ratings stigmatise schools and make improvement even more difficult.
He added: "The Government must reform the inspection system so it is more supportive and less punitive, improve education funding and work with the sector to boost teacher recruitment and retention."
Dr Mary Bousted, joint general secretary of the National Education Union, said: "Ofsted is a bankrupt idea, long discredited by the profession as any sort of arbiter on schools.
"The inspectors are out of touch and the inspections punitive, giving a narrow view of what a school is achieving with its students.
"We are calling on Government to work with us and others to create a new approach to school and college evaluation which is supportive, effective and fair."
Of the 230 schools in Cornwall rated good or higher, two were nurseries, 196 were primary schools, and 22 secondary schools.
There were also four special schools and six schools offering alternative provision graded good or outstanding.
The Department for Education said inspections provide an independent and rounded assessment of schools, which are helpful to both teachers and parents.
A spokeswoman added additional funding would enable Ofsted to inspect all schools between summer 2021 and summer 2025 to provide a complete picture of post-pandemic education.
Ofsted declined to comment.