The present invention provides compositions and methods relating to or derived from antigen binding proteins and antigen binding protein-FGF21 fusions that specifically bind to β-Klotho, or β-Klotho and one or more of FGFR1c, FGFR2c, FGFR3c, and FGFR4. In some embodiments the antigen binding proteins and antigen binding protein-FGF21 fusions induce FGF21-like signaling. In some embodiments, an antigen binding protein or antigen binding protein-FGF21 fusion antigen binding component is a fully human, humanized, or chimeric antibody, binding fragments and derivatives of such antibodies, and polypeptides that specifically bind to β-Klotho, or β-Klotho and one or more of FGFR1c, FGFR2c, FGFR3c, and FGFR4. Other embodiments provide nucleic acids encoding such antigen binding proteins and antigen binding protein-FGF21 fusions, and fragments and derivatives thereof, and polypeptides, cells comprising such polynucleotides, methods of making such antigen binding proteins and antigen binding protein-FGF21 fusions, and fragments and derivatives thereof, and polypeptides, and methods of using such antigen binding proteins and antigen binding protein-FGF21 fusions, fragments and derivatives thereof, and polypeptides, including methods of treating or diagnosing subjects suffering from type 2 diabetes, obesity, NASH, metabolic syndrome and related disorders or conditions.