Burton was originally the daughter of a German Lutheran family who rarely went to church. Apart from Sunday School it is thought that in her childhood she had little interest in religion. She graduated in the late 1900s from Western Reserve College. At that time she considered herself an agnostic and never attended religious services, even after marrying Harry Payne Burton, a journalist and failed Episcopal minister in 1910. Harry was to have considerable trouble during his marriage - which produced three children - eventually committing suicide

During the following decade, she travelled frequently, in the process coming into contact with Selden Delany, the assistant rector at an Episcopal Church in New York City, who was to lead her journey to Catholicism in the coming years. Delany, who died in 1935, converted to Catholicism in the late 1920s and his book Why Rome?, published in 1930, convinced Katherine to convert immediately. She was received into the Church on September 8, 1930, but even before that she wrote two poems, "So Died a True Christian" and "A Prayer for Ronald" (both 1927) that had a strongly Catholic flavour.

Along with her close friend and fellow convert Dorothy Day, Burton was the first major Catholic woman journalist in the United States. In 1933, at the same time as Day established the Catholic Worker, Burton wrote a journal Woman that was published by the Passionist Fathers and advocated motherhood as the greatest possible vocation at a time when it was becoming very difficult for women to raise children due to economic conditions. On the other hand, Burton believed that women should be aided as much as possible if they were forced to seek paid employment outside the home. Katherine Burton in fact believed that balancing work and family was an extremely rich reward for any woman who could do so. Like Day, Katherine Burton was initially a pacifist, but in contrast to Day's consistent stance, Burton relented from pacifism during World War II because she feared the result of the spread of totalitarianism if the US did nothing about it.

Burton was, even before her conversion, interested in the problems women faced with large families, and even before it become the only method of birth control approved by the Church, she was a developer and advocate of the rhythm method of contraception, having known about the fertile and infertile periods of the menstrual cycle ever since her days at college during the 1900s. She also believed that most Roman Catholic writers of her time were stylistically flawed because they were "too arrogant and preachy", with the result that she wrote biographies that read more like fiction.