We reconstruct fault slip rates since ~14 ka on the Sadie Creek fault (SCF), north of the Olympic Mountains, Washington using airborne lidar and field mapping of surficial deposits and landforms and optically stimulated luminescence and radiocarbon dating. The SCF is a ≥14 km-long northwest-striking, subvertical, dextral strike-slip fault with a subordinate dip-slip component. Laterally offset debris flow channels cut into late-Pleistocene and younger surfaces show dextral slip of 4.0–24.5 m and dip slip of 0.7–6.5 m. Reevaluation of fault slip on the adjacent Lake Creek Boundary Creek fault (LCBCF) shows similar dextral (4.5–29.7 m) and dip slip (0.8–4.6 m). A deglacial age of 14 ka paired with the largest – and presumably oldest – slip measurements produces a minimum dextral slip rate of 1.3–2.3 mm/yr and dip-slip rate of 0.05–0.5 mm/yr. Similarities in kinematics, slip rate, and earthquake timing between the SCF and LCBCF suggest these faults represent one continuous geologic structure, the North Olympic fault zone. Geodetically constrained boundary element method models considering the effects of coseismic subduction zone stresses on upper plate structures produce comparable kinematics to those measured on the SCF and LCBCF.