The present invention is directed to a bit-level memory controller and method adaptable to managing defect bits of a non-volatile memory. A bad column management (BCM) unit retrieves a bit-level mapping table, in which defect bits are respectively marked, based on which the BCM unit constructs a bit-level script (BLS) that contains a plurality of entries denoting defect-bit groups respectively. An internal buffer is configured to store data managed by the BCM unit according to the BLS.