Students found cheating during GCSE and A-Level results rose by a quarter in England during the summer of 2017 compared to the same period a year previously.
Exams regulator Ofqual found 2,715 penalties were issued for malpractice compared to 2,180.
Most issues were with mobile phones taken into exams, with four in 10 student penalised. A fifth were disciplined for plagiarism, with 86% occurring in maths and computing exams.
1,235 students were penalised with the loss of marks, 635 students were given a warning and 490 students had their papers scrapped.
Liberal Democrat education spokesperson Layla Moran said: “This is an extremely worrying trend in our exam halls and throws into question whether the current assessment process is even fit for purpose.”
The rise in students cheating comes in the wake of tougher GCSEs in English, introduced for the first time.