How to Get a SharePoint Online External Sharing Report

Native Solution

Netwrix Auditor for SharePoint

Steps

Natively, it is not possible to generate a report on external sharing across your entire tenant. Instead, you have to generate and download a report for each SharePoint site collection separately:

Open the site you want to report on.
Click the cog icon to open Settings menu andthen click Site usage.
Scroll down to the Shared with external users section and click Run report.
Pick a location to save the report and click Run report.
Browse to the SharePoint Online location where you chose to save the report.
Review the CSV report in Excel, filtering out default records (such as site Owners, Members and Visitors):

To get a report on external sharing across all sites in your tenant:

Run Netwrix Auditor -> Navigate to “Reports” -> Choose “Predefined” -> Expand the “SharePoint Online” section -> Go to “SharePoint Online – State-in-Time” -> Select “SharePoint Online Site Collections External Sharing” -> Click “View”.

To get a report on external sharing report for a specific site collection, do either of the following:

You can drill down to specific site level report by click the site collection link in the cross-tenant report.

Alternatively you can go directly to site-level report:

Netwrix Auditor -> Navigate to “Reports” -> “Predefined” -> Expand the “SharePoint Online” section -> “SharePoint Online – State-in-Time” -> Select “Objects Shared with External or Anonymous Users” -> Click “View”.
Specify the site URL in the “Site collection object path” field -> Click “View Report”.

Sample site-level report:

Get a SharePoint Online External Sharing Report to Prevent Leaks of Sensitive Data

Microsoft 365 (former Office 365) provides great collaboration capabilities: Within minutes, users can create a new SharePoint site, add a blog or document library, and upload and share files. External sharing in SharePoint Online and OneDrive for Business is very easy as well; access can be provided to specific users or via anonymous links — which enable anyone who has the link to access resources without any authentication at all. To minimize serious risks, including leaks of sensitive data, SharePoint administrators have to keep a close look at all external sharing.

Natively, there is no SharePoint Online external sharing report. Instead, you can generate a usage summary using the SharePoint admin center. However, to get the full picture of external sharing across your Office 365 tenant, you’ll have to generate this summary for each site collection separately, merge the results, and then manually filter out External and Anonymous shares (since SharePoint creates sets of permissions for site Owners, Visitors and Members based on your security policy). Also, because Microsoft 365 creates several audit records for a single sharing event, you will need to do some extra work to match sharing links to particular users.

Netwrix Auditor, on the other hand, will provide you with a comprehensive and easy-to-read Office 365 external sharing report for your entire tenant in just a few clicks. The report shows all site collections with any type of external shares, and you can drill down to any specific site collection simply by clicking its name. There, you can see all the critical details about the external sharing, including the user who shared the file, the permissions granted and when the shared link expires.

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