Mililani Mauka is located at (21.4756, -157.9947). According to the United States Census Bureau, the CDP has a total area of , all land. Mililani Mauka lies within the Ewa Moku on Oʻahu, more specifically the Waipio Ahupuaʻa.Julie Stewart Williams, From The Mountains To The Sea Early Hawaiian Life (Kamehameha Schools Press, 1997), 9.
