The social network's founder published - on his Facebook page - what amounted to a greater commitment to users' safety following several "heartbreaking" instances of people hurting themselves or others in live, or recorded, videos in recent weeks.
He said the investment - announced hours before the company's latest financial results were published - would also include a greater emphasis on tackling hate speech and child exploitation.
Mr Zuckerberg wrote: "If we're going to build a safe community, we need to respond quickly.
"We're working to make these videos easier to report so we can take the right action sooner - whether that's responding quickly when someone needs help or taking a post down.
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"Over the next year, we'll be adding 3,000 people to our community operations team around the world - on top of the 4,500 we have today - to review the millions of reports we get every week, and improve the process for doing it quickly."
He added: "Just last week, we got a report that someone on [Facebook] Live was considering suicide.
"We immediately reached out to law enforcement, and they were able to prevent him from hurting himself. In other cases, we weren't so fortunate.
"No one should be in this situation in the first place, but if they are, then we should build a safe community that gets them the help they need."
The statement will be largely seen as an admission by Facebook that action was overdue.
Last week, a father in Thailand broadcast himself killing his daughter on Facebook Live.
The company removed the video a day later after more than 370,000 views.
There have been many other examples including a live stream, in January, of a man with learning difficulties being bound, gagged and brutally punched .
Last month, a video was uploaded of a man being shot dead in an unprovoked attack .
A report by a House of Commons committee has recommended social media firms are fined if they fail to tackle illegal or harmful material.
Facebook-owned WhatsApp has also come under pressure after it emerged Westminster terror attacker Khalid Masood sent an encrypted message via the messaging service just minutes before his rampage.
Google, too, has also been at the centre of a boycott by some advertisers angry that their messages have appeared alongside extremist content on the company's video-sharing site YouTube.
Facebook's latest results highlighted the scale of the monitoring challenge ahead - with 1.94 billion active monthly users in the three months to the end of March.
It said total revenue jumped 49% to just over $8bn - with mobile advertising revenue now accounting for a growing share of its ad base, at 85%. Net (LSE: 0LN0.L - news) profits were almost 80% up at $3.1bn.