The first Christian missionaries arrived on Maui in 1823. The Reverends William Richards and Charles Stewart, sent by the American Board of Commissioners for Foreign Missions, made Lahaina the first Protestant mission station on the island. Olowalu shortly thereafter became an outstation of the Lahaina mission. As an outstation, Olowalu did not have its own minister, instead relying on visits from Lahaina missionaries who would travel by canoe for two hours to preach and teach. A succession of Lahaina missionaries successfully converted the Hawaiians of Olowalu, holding services on a heiau.
In 1835 Reverend Ephraim Spaulding built a 26-foot by 43-foot church at Olowalu, with the intention of using it as both a church and school. He used adobe and lepo (either dung or clay) to build walls three feet thick. Over time, Hawaiian ministers replaced the Lahaina haole missionaries and in 1858 a stone building replaced the original structure. Ten years later, the 250 members of the Olowalu Church broke with the Lahaina Mission Station and became an independent church named the Olowalu Hawaiian Protestant Church.
Olowalu Church continued to serve the community in the latter part of the 19th century with Hawaiian ministers providing services in the Hawaiian language. In 1876 a minister named Keaupuni served the church, one of 10 active Congregational churches on Maui. For the last two decades of the century, Reverend S. K. Kamakahiki served the church. In 1897 the independent Olowalu Hawaiian Protestant Church re-affiliated itself with the Waine`e Church (now called Waiola Church) in Lahaina.
In 1930 a spark from burning cane destroyed the wooden roof of the Olowalu Hawaiian Protestant Church. Members of the congregation continued to hold services where they could. In 1934 the church bought the empty Olowalu School and held services in the teacher's cottage until 1948.
The New England Protestants were not the only missionaries to the Hawaiians. In 1827 French Catholic missionaries landed on O`ahu. Initially persecuted by Protestants, Catholicism eventually gained a foothold with thousands of converts throughout Hawai`i.
A lay preacher named Helio Koaeloa, converted to Catholicism on `Oahu, zealously spread Catholicism throughout Maui, including Olowalu, beginning in the late 1830s. In 1846 three Catholic missionaries established the first official Catholic mission on Maui in Lahaina. One of these pioneers, Father Modest Favens, immediately reached out to rural areas, visiting Olowalu and baptizing converts during the mission's first year of 1846. In 1916, 60 years after the first Catholic baptism, a permanent Roman Catholic church was built at Olowalu on the makai side of the road, a short distance from the Wailuku side of the mill. At that time, Father Bruno Bens of the Lahaina mission supervised the construction of a church dedicated to Saint Joseph.
The Mormons began their mission work in Hawai`i on Maui in 1851 and the number of converts initially grew rapidly. The Church of Jesus Christ of Latter Days Saints maintained a presence in Olowalu into the 20th century. Olowalu was one of eight branches of the West Maui Division of the church in 1921.