Microsoft 365, formerly Office 365, is a line of subscription services offered by Microsoft which adds to and includes the Microsoft Office product line. The brand was launched on July 10, 2017, for a superset of Office 365 with Windows 10 Enterprise licenses and other cloud-based security and device management products.

On April 21, 2020, the consumer and small business plans of Office 365 were renamed Microsoft 365 to emphasise their current inclusion of products and services beyond the core Microsoft Office software family (including cloud-based productivity tools and artificial intelligence features). Most products that were called Office 365 were renamed as Microsoft 365 on the same day.

Microsoft 365 encompasses subscription plans that allow the use of the Microsoft Office software suite over the life of the subscription, as well as cloud-based software-as-a-service products for business environments, such as hosted Exchange Server, Skype for Business Server, and SharePoint, among others. All Microsoft 365 plans include automatic updates to their respective software at no additional charge, as opposed to conventional licenses for these programs—where new versions require the purchase of a new license.

The Office 365 branding remains in use for subscription plans targeting some enterprise markets.