Disclosed are compounds, compositions, and methods involving cyclic peptides that can bind to KRAS (G12D) oncogenic protein. For example, disclosed are cyclic peptides that selectively bind KRAS (G12D) oncogenic protein. Also disclosed are methods of inhibiting KRAS (G12D) oncogenic protein in a cancer cell expressing KRAS (G12D) oncogenic protein. In some forms, the method comprises incubating the cancer cell with any one or more of the disclosed cyclic peptides. In some forms, the method comprises bringing into contact the cancer cell with any one or more of the disclosed cyclic peptides.