Dan McNamara, president of the Detroit Fire Fighters Association, called the Monday announcement "indefensible."
"These cuts by the city will put its Fire Department and its residents at great risk -- increasing response times and further taxing an already greatly reduced work force," McNamara said in a statement.
Bing said he hopes the city wins a federal grant allowing the department to rehire 108 of the positions, the Detroit News reported.
"Since I became mayor, I've made public safety my top priority, and I've said I would protect the jobs of police and firefighters, but fiscal realities have made this untenable," Bing said.
Detroit's 2012-13 budget includes $250 million in cuts from nearly every department, meaning the loss of about 2,600 jobs. The fire department's budget will be trimmed to about $160 million, the newspaper said.