Google parent Alphabet Inc. said it plans to eliminate roughly 12,000 jobs, reducing its staff by 6% and marking the company’s largest-ever round of layoffs as it copes with a darkened economic outlook.

The reductions will cut across Alphabet units and geographies, the company said, though some areas, including recruiting and projects outside of the company’s core businesses, would be more heavily affected. 

The cuts follow a wave of layoffs at other technology companies in recent months, including Microsoft Corp. , Amazon.com Inc. and Meta Platforms Inc.

Those cuts have been part of a broader pivot toward protecting profit and cementing the end of a growth-at-all costs era in technology. Google executives have in recent months said the company would be tightening its belt, reflecting a new period of more disciplined and efficient spending. But the company hadn’t announced cuts as deep as those of its Silicon Valley peers. 

“Over the past two years we’ve seen periods of dramatic growth. To match and fuel that growth, we hired for a different economic reality than the one we face today,” Alphabet Chief Executive Sundar Pichai wrote in a message to employees being sent out Friday and seen by The Wall Street Journal.

Alphabet earlier this month said it would cut more than 200 jobs at its Verily Life Sciences healthcare business, accounting for about 15% of the roles at the unit. Before that, some of the last major cuts Google announced were in 2009, when the company said it was reducing the number of jobs in its sales and marketing teams by roughly 200 globally.

Friday’s cuts at the Google parent come just days after Microsoft said it would cut 10,000 jobs in response to a global economic slowdown. Earlier this month, Amazon said that its round of layoffs would affect 18,000 roles. Employers in the tech sector have cut nearly 195,000 jobs collectively in the past year, before taking into account Alphabet’s cuts, according to estimates from Layoffs.fyi, which tracks media reports and company announcements.

As job cuts have accumulated in the tech industry, many employees at Google have pressed executives about the possibility of layoffs at the company. At a companywide meeting in December, Mr. Pichai told employees that the company had tried to “rationalize where we can so that we are set up to better weather the storm regardless of what’s ahead.”

A Google spokesman said that Friday’s cuts would affect not just Google, but also other Alphabet subsidiaries, but didn’t specify at what levels. Alphabet subsidiaries include Verily and the Waymo self-driving-car unit. The spokesman didn’t comment on which specific products or engineering units would be affected.

Alphabet said it would offer U.S.-based employees two months notice, plus 16 weeks of severance pay, along with two additional weeks for each year an employee being laid off from the nearly 25-year-old company has worked there. In other countries, the company will follow local processes and laws, which sometimes require consultations with employee representatives before workers are laid off.

The company will also offer former employees access to resources to help them with their immigration status, job placement and mental health, the spokesman said. Tech companies in the U.S. often have employees on work visas tied to their employment.

Write to Sam Schechner at Sam.Schechner@wsj.com