MacKay and New Democrat MP Robert Chisholm are joining members of the United Steelworkers in spreading awareness that companies are legally responsible for keeping their workers safe from harm.
An explosion in the Westray coal mine in Plymouth, N.S., killed 26 miners on May 9, 1992.
MacKay says he knew some of those who died.
The Nova Scotia MP says the tragedy was preventable and the safety legislation passed afterwards was a landmark in making work safer.
But he says much remains to be done.
"We need to continue to work with businesses and provinces, safety inspectors, all partners across this country to make workplaces safer," he said.
The minister said companies have serious responsibilities to keep workers safe.
"Safety is necessary, it's good business and to ignore it has criminal consequences," he said.
Note to readers: This is a corrected story. An earlier version said NDP MP Megan Leslie took part in the event