The Windsor-Essex Catholic District School Board has never had 90 per cent of students graduate at its high schools, before now.
The Ontario Ministry of Education released graduation rates after four and five years Thursday.
At the Catholic school board, 90.5 per cent of students got their high school diploma after five years; 89.1 per cent after four.
That is well above the provincial average of 81.2 per cent after four years, and 87.1 per cent after five.
"We've never exceeded that 90 per cent threshold, so we're delighted to see these numbers," said Emelda Byrne, executive superintendent of education. "Graduating high school is a major determinant of future success."
The numbers also show an increase over last year when 79.8 per cent of students earned a diploma after four years of high school, and after five years, 86.3 per cent.
At the Greater Essex County District School Board, 79.2 per cent of high school students successfully earned their Ontario Secondary School Diploma in four years, while 85.5 per cent received it in five years.
In 2016, the previous numbers posted on the Ministry's website, 78.2 per cent got their diploma after four years of instruction. Two years ago, 86.1 per cent earned it after five.
The highest graduation rates in the province were at the York Catholic District School Board where 94.7 per cent of students graduated after four years, and 96.5 at the end of five years.