United's Toronto operations will lose 95 jobs, Vancouver will lose 84 positions, and Calgary will see 61 jobs cut.
“These were difficult decisions, but necessary as we must continually look for new opportunities to run a more efficient and financially sustainable business,” the airline said in an email statement to CBC News.
"Based on a competitive bid, United made the difficult decision to outsource the above- and below-the-wing functions at three Canadian stations: Vancouver, Calgary and Toronto."
The airline said it would be "talking to the vendor" about providing preference to laid-off United employees for jobs.
No flights are being cut.
Air Canada and United Airlines are in a joint venture that includes co-operation and revenue sharing on transborder flights between the two carriers. Both airlines are part of the Star Alliance,
United Airlines became the world's biggest airline following its 2010 merger with Continental Airlines but was surpassed by American Airlines when it emerged from bankruptcy last year.