Even so, the economy still saw employment growth of 1.6 per cent over the year with 289,000 more jobs created.
The agency provided data showing the province gained approximately 8,500 full-time positions but lost roughly 59,300 part-time ones, noting that the figures are rounded. While the unemployment rate in December was 8.6 per cent, month-over-month comparisons are hard to make as data is unadjusted for seasonal differences that can influence each month.
Overall, the latest labour market data "bring the job market back down to Earth, and reinforces the view that the Bank of Canada will proceed ultra-cautiously through the rest of this year", Porter wrote.
However, economists also pointed to possible connections between Ontario's minimum wage and Canada's stronger average wage growth of 3.3 per cent in January.More news: Apple's new Battery Health featured in iOS 11 beta
"The concentration of the job loss in Ontario and the focus upon lost part-time jobs in that province will no doubt feed debate on whether large minimum wage hikes took a toll on employment, but proving causality may remain contentious", Derek Holt, Scotiabank's head of capital markets economics, said in a commentary.
The drop in employment raised the unemployment rate up by 0.1 percent to 5.9 percent, a marked difference from November and December, when a total of 145,000 jobs were added, according to CTV.
Rocco Rossi, president of the Ontario Chamber of Commerce, said the numbers "reflect the concerns we have heard from businesses for months".
Despite Canada's healthy economic performance past year, Alexander said the surprising pace of job creation had been stronger than the other data.More news: Pelosi to oppose sweeping budget deal over lack of protections for DREAMers
In a labour force of 39,200, this region saw 37,700 people employed in January - while 1,500 were unemployed.
"I don't think that the January number is the start of a whole series of declines - I think it's more of a reflection of the fact that we were tracking abnormally strong numbers behind us", Alexander said.
The unemployment rate in Kitchener-Waterloo fell to 5.1 per cent, but only because of 2,600 drop in the local labour force. Others didn't expect the January report, on its own, to have a significant impact on the outcome of the next rate announcement. He said it reinforces the view that the Bank of Canada will proceed "ultra-cautiously" through the rest of 2018.
Ontario recorded the biggest decline last month, down 51,000 -all part-time.More news: No, we don't need a tank parade
Don't blame the minimum-wage hike just yet.