Kahili Adventist School began as Kapaa Mission School in 1938. The school has had several names and several locations since then. In 1984, facing a shortage of space at its Omao school, and responding to island educational needs, a long-term lease was negotiated with the Knudsen Trust to establish a school on the 197-acre (80 ha) property in the shadow of Kahili Mountain. Students began attending grades K–8 at the Kahili location in 1986. A building project was completed in several phases over the next few years, with the first phase official opening ceremonies taking place in 1987. The school has continued to grow, remodeling the old lodge for classes and adding additional classrooms and gymnasium. In 1992, Kahili instituted high school grades at the same location, making Kahili the oldest private K–12 school on Kauai.
The school is a member of the Hawaiian Association of Independent Schools and is accredited by the Hawaii Council of Private Schools, The Board of Regents of the General Conference of Seventh-day Adventists among other accrediting organizations. Kahili is affiliated with Hawaiian Mission Academy on Oahu for the granting of high school diplomas.