LinkedIn is the latest website to add two-factor authentication as a measure to prevent account takeovers.
The company on Friday announced the new functionality, saying in a blog post that it will make it "more difficult for unauthorized users to access your account."
LinkedIn users will be queried for an additional verification code, in addition to their password, when they attempt to login to the site from an unrecognized computer or device. The code will be sent to users via mobile text message.
The site's more than 200 million members can enable the capability by visiting "Settings," then selecting the "Account" tab and clicking "Manage Security Settings."
The business networking service has tightened its security since it sustained a massive breach earlier this year when 6.5 million of its users' passwords were dumped on a Russian forum. Victims were forced to reset their passwords.