The Senate passed legislation on Monday night ordering an end to the rotating strikes by Canada Post workers that has lasted five weeks.
The legislation goes into effect Tuesday at noon.
After two days of special sittings to debate the matter, Senators voted 53-25 in favour of the Bill, with four abstentions.
The bill was rushed through the House of Commons last week.
The government deemed the passage of the bill to be urgent due to the economic impact of continued mail disruptions during the busy holiday season.
The Canadian Union of Postal Workers says the legislation is unconstitutional and has vowed to challenge it in court.
With reporting from Virginia Wright
