Your friends list is public by default and it is the first thing a stranger opens. Paste your own profile link below to see whether yours is showing, then follow the steps to hide it.
Tap your profile picture in the top right, then tap Settings and privacy, then Settings.
Scroll to Audience and visibility and tap How people find and contact you.
Tap Who can see your friends list.
Choose Only me. Friends is the middle option if you want friends to keep seeing it.
Go back to your profile and open the Friends tab. The list now shows only to you.
On the web
Click your picture in the top right, then Settings and privacy, then Settings.
Open Privacy in the left column and click How people find and contact you.
Next to Who can see your friends list, click Edit and pick Only me.
What still shows after you hide it
Mutual friends. Anyone who shares a friend with you sees that friend on your profile, because the connection belongs to both of you. There is no setting for it. Your name also keeps appearing on your friends' lists, so someone can read your circle from a friend's public list if that friend left it open.
Followers are separate from friends. If you allow followers, the Followers count stays on your profile, and the list of followers has its own setting under the same page.
Two related settings on the same page
Who can send you friend requests: Everyone or Friends of friends.
Who can look you up using the email address or phone number you provided: set both to Friends or Only me to stop strangers matching your number to your profile.
Common questions
Can people still see our mutual friends after I hide my list?
Yes. Mutual friends are shown to anyone who shares them with you, and no setting removes that.
Will my friends know I hid my friends list?
No. Facebook does not send a notification, and the tab simply shows fewer names.
Does hiding my friends list hide my followers?
No. Followers have their own setting on the same page, and the Followers count on your profile stays.
Can a friend's public list still show that we are friends?
Yes. Your name sits on their list under their setting, not yours. That is why hiding your own list is only half the job.