Miss Barnett was born in Aberdeen, Scotland. She arrived in Taiwan in 1887 and started the Sinlou Girls School (新樓女學校, today named Chang Jung Girls Senior High School, Tainan) project with Miss Joan Stuart and Miss Annie Butler.

This school was the first Western-style school for women in southern Taiwan; She served in Taiwan for 45 years. She was buried in the Tainan missionaries' cemetery.