Top grades in England, Wales, and Northern Ireland (7/As and above) rose to 28.9 per cent from 26.2 per cent last year, while grades 4/Cs and above rose to 77.1 per cent up from 76.3 per cent.
In a statement, the Pickering school said: "We congratulate all students on their achievements in this most extraordinary of years. Year 11 have had to develop and demonstrate a great deal of resilience and independence as they have studied through two national school closures and remote learning."
Exams were again cancelled this year due to the coronavirus pandemic and teacher-assessed coursework was used instead.
Lady Lumley's School paid special mention to several high-achieving students.
• Felicity Lloyd achieved nine GCSE passes at grade 9 and one at grade 8
• Freya Botzen and Lucy Hinchliffe each achieved seven grade 9 passes and three at grade 8
• Ellie Capsey, Isabelle Hutchinson and Harrison Archer were congratulated for "exceptional progress".
The school continued: "Students have achieved these grades at the end of their Year 11 education and have upheld the strong outcomes the school has always enjoyed.
"We are absolutely delighted for all our students and recognise their achievements today, both for the grades they have got and the qualities they have demonstrated.
"We have encouraged our students to try their best, take on the advice and support offered and believe in themselves. Those who did this should be pleased with their results and excited for the next stage in their education."