Memory devices and systems with post-packaging master die selection, and associated methods, are disclosed herein. In one embodiment, a memory device includes a plurality of memory dies. Each memory die of the plurality includes a command/address decoder. The command/address decoders are configured to receive command and address signals from external contacts of the memory device. The command/address decoders are also configured, when enabled, to decode the command and address signals and transmit the decoded command and address signals to every other memory die of the plurality. Each memory die further includes circuitry configured to enable, or disable, or both individual command/address decoders of the plurality of memory dies. In some embodiments, the circuitry can enable a command/address decoder of a memory die of the plurality after the plurality of memory dies are packaged into a memory device.