Step by step instructions below.
Step 1: Download Absinthe 2.0 for Windows from this page .
Step 2: Extract, and right click on the absinthe-win-2.0.exe icon and select Run as Administrator. This first file is a self extracting zip file. Once you do this, a new folder will be created on your desktop called absinthe-win-2.0 with the necessary files.
Step 3: Open the absinthe-win-2.0 and right click on the absinthe.exe icon and select Run as Administrator.
Step 4: Connect your eligible iOS 5.1.1 device, and verify that Absinthe recognizes the correct name of your device.
Step 5: Click the jailbreak button on Absinthe, and let it run. You should see a progress bar.
Step 6: Eventually your device will appear as if it’s performing a restore, this is normal.
Step 7: Once the device has completed the “restore”, you should notice the Cydia icon on your Home screen.
Step 8: Once Absinthe reports that the process is complete, you can close Absinthe and disconnect your device.
Step 9: Open Cydia and let it configure itself for the first time. Congratulations, your iOS 5.1.1 device is now jailbroken untethered!
Were you able to successfully jailbreak your iOS 5.1.1 device on Windows? Let us know how you fared in the comments below.