As the result of an epiphany one night, which she described as “neither a dream nor vision”, she embraced the Baháʼí Revelation and accepted it as God's new message to humanity as proclaimed by Baháʼu'lláh.
Alexander was an early advocate of Esperanto and used that new international language to help spread Baháʼí teachings at meetings, conferences, and in articles.
In 1964, Alexander represented the Universal House of Justice, the supreme administrative body of the Baháʼí Faith, at the election of Hawaii's first National Spiritual Assembly in Honolulu.
After suffering a broken hip in 1965, and spending two years in a Tokyo hospital, Agnes Alexander returned to her birthplace in Honolulu in 1967.
[5] At the request of Shoghi Effendi, Agnes Alexander wrote two histories: "Personal Recollections of a Bahá’í Life in the Hawaiian Islands: Forty Years of the Bahá’í Cause in Hawaii, 1902-1942"[6] and "History of the Baháʼí Faith in Japan, 1914-1938".