Samsung Electronics GmbH
Hello,
Thank you for your enquiry.
The Samsung SSD 870 EVO SATA III 2.5 inch - 250 GB MZ-77E250B/EU is compatible with the MacBook Pro 15 inch, mid 2012 (MacBookPro9,1).
For the Samsung SSD 870 EVO SATA III 2.5 inch, your device requires a SATA 6 Gb/s interface, whereby the SSD is also compatible with a SATA 3 Gb/s & SATA 1.5 Gb/s interface, as well as a free installation slot in the 2.5 inch form factor.
Other compatible SSD models are the Samsung 870 QVO and the Samsung 860 PRO.
If in doubt, please contact Apple customer service.
Best regards from Eschborn
Your Samsung Service Team

The Samsung 870 EVO SSD (250 GB, 2.5 inch) is basically compatible with a mid-2012 MacBook Pro as it uses the SATA III interface supported in this model. However, the installation may require additional hardware such as a SATA adapter or a bay for the SSD, as the MacBook Pro is originally equipped with an optical drive. It is advisable to ensure that all necessary components are present before installation.