The Liberals temporarily waived the 20-hour cap on work hours for international students during the COVID-19 pandemic in a bid to ease labour shortages.
That waiver expires Tuesday.
"Looking at best practices and policies in other like-minded countries, most of them limit the number of working hours for international students. Canada's rules need to be aligned or we will find our programs attracting more and more applicants whose primary intent is to work and not study," Miller said.
"To be clear, the purpose of the international student program is to study and not to work."
The new work limit comes as the federal government clamps down on a surge in international student enrolments across the country.
Critics have warned that allowing international students to work full-time could turn a study permit into an unofficial work visa, which would undermine its purpose.
However, the federal government is also hearing from international students who say they need to work more to pay for their studies.
Miller said his government is setting the cap at 24 hours because that seems "reasonable," and would allow students to work three full eight-hour shifts a week.
He also noted that internal work by the department shows more than 80 per cent of international students are currently working more than 20 hours a week.
The work hours limit will return to 20 hours per week until September, when the government can implement a permanent change to make it 24 hours.
There are no limits on the number of hours international students can work when they're not actively enrolled in class, such as during the summer.
The Canadian Press reported earlier this year that officials in Miller's department warned the government in 2022 that the temporary waiver could distract students from their studies and undermine the objective of temporary foreign worker programs.
Miller previously floated the idea of setting the cap permanently at 30 hours a week. However, on Monday, the immigration minister said that would be too close to full-time hours.
"We know from studies as well that when you start working in and around 30-hour levels, there is a material impact on the quality of your studies," he said.
Miller extended the waiver on work hours in December because he didn't want the change to affect students during the school year itself.
