CTU said school would still be in session that day.
The union said CPS would be providing buses for students and educators to attend a rally at 1 p.m. in Union Park and that there would be no retaliation for students or staff who participate.
CPS said that schools wishing to participate must follow the existing CPS student travel policy and normal field trip procedures.
"This agreement preserves the classroom time students deserve and respects our staff and families who must be able to trust CPS to uphold the academic school year calendar," said CEO/Superintendent Dr. Macquline King. "At the same time, the agreement honors the proud history of civic action in Chicago and beyond."
CPS said participation in any civic events is voluntary and parental permission is required.
Mayor Brandon Johnson said in a statement, "We are pleased all parties are working together to ensure school communities can participate in commemorating International Workers Day. Schools will remain open for instruction, while multiple opportunities will be provided for those who wish to participate in this day of civic action both inside and outside of the classroom.
"Encouraging participating allows Chicagoans to honor our history while advocating for our future. We look forward to a day of meaningful solidarity and community resistance to the forces trying to tear us apart.
"The history of May Day in America is rooted in Chicago. It was in our city that workers organized around the simple demand of an eight-hour workday and raised the consciousness of a gilded nation through the Haymarket Strike.
"We continue to work with all City Agencies and Departments to ensure a safe and impactful May Day."