The present disclosure provides antibodies (e.g., humanized antibodies) that specifically bind to Mer Tyrosine Kinase (MERTK; e.g., human MERTK) and compositions comprising such antibodies. The present disclosure also provides antibody-drug conjugates comprising (i) an anti-MERTK antibody or antigen-binding fragment thereof described herein that specifically binds to MERTK (e.g., human MERTK), and (ii) cytotoxic agents conjugated directly to the antibodies or conjugated to the antibodies via linkers, and compositions comprising such antibody-drug conjugates. The present disclosure also provides methods for treating cancer, comprising administering to a human subject in need thereof (a) an anti-MERTK antibody that specifically binds to MERTK (e.g., human MERTK) or an antigen-binding fragment thereof described herein, or (b) an antibody-drug conjugate that comprises (i) an anti-MERTK antibody or antigen-binding fragment thereof that specifically binds to MERTK (e.g., human MERTK), and (ii) a cytotoxic agent conjugated directly to the antibody or conjugated to the antibody via a linker.