Created in consultation with British charity Samaritans, the tool will allow users to report content to Facebook or reach out to their friends.
"We worked with organisations including Samaritans to develop these tools, and one of the first things they told us was how much connecting with people who care can help those who are struggling to cope - whether offline or online," said Julie De Bailliencourt, head of safety at Facebook.
Facebook and Samaritans have collaborated on a suicide prevention feature since 2011.
If a person on Facebook thinks a friend is in need of support, then they can use a form in Facebook's Help Centre to flag their concern to Facebook or report their concern via the reporting links found across Facebook's site.
Reports to Facebook are triaged and those reported that where someone may be at risk are prioritised.
"If someone is reported to us, as at risk of suicide, Facebook's safety team will look at their account. If they consider that a person is at risk of immediate harm then we may, in very rare cases, alert local police," Samaritans wrote on its website.
"If we don't consider that someone is at immediate risk but is showing signs of distress then we will interrupt their Facebook experience. At this time we will send them a message to say that a friend has flagged that they may be in crisis and offer them information about how to get help via Samaritans," it further added.
If you report worrying content, users will be sent a notification asking them whether they need support from a friend or helpline, and will be given tips and advice on how to deal with suicidal thoughts or thoughts of self harm.
"Those who report explicit threats of suicide will be given the number for emergency services, while less serious content will be flagged to Facebook," the charity noted.
In 2014, the charity launched an initiative with Twitter which flagged "worrying tweets" to the service but was withdrawn later.