Carcinoembryonic antigen–related cell adhesion molecule 1 (CEACAM1) is a cell surface glycoprotein involved in intercellular binding, belonging to the immunoglobulin superfamily. It is involved in cell-cell recognition and modulates cellular processes that range from vascular angiogenesis to the regulation of insulin homeostasis and T-cell proliferation. Aberrant expression of CEACAM1 is often associated with progression and metastatic potential in melanoma, lung carcinoma and other types of tumor. Tumor-specific antigens such as CEACAM1 are ideal targets for cancer immunotherapy because they are over-expressed by the cancer cell and not on non-malignant tissues, minimizing the risk of autoimmune destruction. Many of the limitations of therapeutic use of rodent monoclonal antibodies (mAbs) can now be overcome by exploiting the use of recombinant antibody fragments and the advances in antibody engineering methods to improve tumor retention, reduce immunogenicity and modulate pharmacokinetics. In addition, a novel effective model of immunotherapeutic treatments of tumors includes antibody drug conjugates (ADCs) that combine specific mAbs and antibody fragments with cytotoxic drugs, proteins, enzymes, radionuclides and nanoparticles. This review aims to describe how these antibody engineering approaches can meet the challenges for generating new and effective antibody constructs for diagnosis and therapy of CEACAM1 expressing malignancies.