Windows 7 was the first Windows version to ship with Windows PowerShell built in.
The integrated release was PowerShell 2.0, which Microsoft completed and released to manufacturing in 2009 as part of Windows 7 and Windows Server 2008 R2. Users no longer needed to download PowerShell separately on those systems, making it a standard administration tool from the first installation.
PowerShell began under the code name “Monad” and was publicly demonstrated in 2003. PowerShell 1.0 became available in 2006 for Windows XP SP2, Windows Server 2003 SP1, and Windows Vista, but those operating systems received it as a separate installation or optional component rather than having it built in by default.
Windows 8 later included PowerShell 3.0, adding capabilities such as scheduled jobs and improved remoting. Windows PowerShell 5.1 was bundled with Windows 10. This history explains a common mix-up: Vista was an early supported platform, but Windows 7 was the first mainstream Windows client release to include PowerShell as an integral component.