Amazon. com Inc.’s layoffs will affect more than 18,000 employees, the highest reduction tally revealed in the past year at a major technology company as the industry pares back amid economic uncertainty.

The layoffs are concentrated in the company’s corporate ranks and represent roughly 5% of that element of its workforce, and 1.2% of its overall tally of 1.5 million employees as of September.

The Seattle-based company in November said that it was beginning layoffs, with the cuts concentrated in its devices business, recruiting and retail operations. At the time, The Wall Street Journal reported the cuts would total about 10,000 people. Thousands of those cuts began last year.

The rest of the cuts will bring the total number of layoffs to more than 18,000 and will be made over the coming weeks.

On Wednesday, after the Journal broke the news about the size of Amazon’s layoffs, Chief Executive Andy Jassy addressed the cuts in a blog post. “Amazon has weathered uncertain and difficult economies in the past, and we will continue to do so,” said Mr. Jassy. He added that the majority of the cuts are on the retail and recruiting areas of Amazon. The blog post said the company would alert affected employees later this month.

Amazon was one of the biggest beneficiaries of the Covid-19 pandemic as customers flocked to online shopping. The rush to Amazon’s various businesses, from e-commerce to groceries and cloud computing, pushed forward years of growth for the company. To keep up with demand, Amazon doubled its logistics network and added hundreds of thousands of employees.

When demand started to wane with customers moving back to shopping in stores, Amazon initiated a broad cost-cutting review to pare back on units that were unprofitable, the Journal reported. In the spring and summer, the company made targeted cuts to bring down costs, shutting physical stores and business units such as Amazon Care. Amazon later announced a companywide hiring freeze before deciding to let employees go.

Many tech companies have cut jobs as the economy sours. Amazon’s layoffs of more than 18,000 employees would represent the highest number of people let go by a tech company in the past few months, according to tallies released on Layoffs.fyi, a website that tracks the events as they surface in media reports and company releases.

The trend has affected companies such as Amazon and others that have acknowledged they grew too quickly in many cases. Facebook parent Meta Platforms Inc. said it would cut more than 11,000 workers, or 13% of its staff, adding to layoffs at Lyft Inc., HP Inc. and other tech companies. On Wednesday, Salesforce Inc. said that it was laying off 10% of its workforce. Co-Chief Executive Marc Benioff

said the business-software provider hired too many people as revenue surged earlier in the pandemic. “I take responsibility for that,” he said.

Write to Dana Mattioli at dana.mattioli@wsj.com and Jessica Toonkel at jessica.toonkel@wsj.com