In 1883, she became a teacher at her alma mater, Lancaster School, and taught there for three years. While teaching she continued to work for the Women's Union, volunteer at St. Luke and study accounting at night school. On September 14, 1886, Maggie married Armstead Walker, a building contractor. They had three sons, one of which died in infancy.
In 1899, the thirty-second annual convention of the Grand United Order of St. Luke was held in Hinton, West Virginia. Walker had worked her way up the ranks of the Order and was elected Right Worthy Grand Secretary-Treasurer at the convention. The Order was renamed the Independent Order of St. Luke. Because the order was in debt, she served in the position at one-third the salary, receiving eight dollars a month. Walker was responsible for implementing successful programs for the Order, causing it to progress. She traveled to organize councils and encourage new people to join. Her speaking ability became her trademark. As a result of her business acumen, the Order became financially successful. The business consisted of an insurance component, a printing press, a newspaper and an Educational Loan Fund for college students. She also organized the Juvenile Branch of the Order. When speaking at Juvenile Society meetings, Walker would encourage the youth to save money. A special day was set aside called Sunshine Day on which the youth sent out a ray of sunshine by visiting the sick or taking food to a needy family. She established an Order newsletter called the "St. Luke Herald." The newsletter devoted a section to children, where their articles, stories, and poems were featured. By 1922, the death claims of the insurance department were nearly $1 million. By 1924, the Order had 50,000 members, 1500 local chapters and assets of almost $400,000.
