The Seattle Federation of Churches was founded in 1919, at a time when such ecumenical councils were being organized across the country and world wide. The constitution of the new federation stated as its purpose "to promote the welfare, comity and cooperation of the churches and to foster religious movements and Community betterment."

In 1928 two state-wide ecumenical organizations, the Inland Empire Council of Christian Education and the Western Washington Council of Religious Education merged and became known as the Washington-Northern Idaho Council of Christian Education. The Rev. Gertrude Apel was elected general secretary in 1929 and served until 1958. The Rev. Apel also served as secretary to the Seattle Federation of Churches, which functioned as a local branch. During these years there occurred mergers and consolidations of many state and local ecumenical programs, and an eventual blurring of the separation between the programs of the regional council and the Seattle federation.

From the beginning the church council supported local churches in such pastoral endeavors as Christian education and chaplaincy programs. Community involvement addressed a wide range of issues, from personal morals and civic betterment to international issues of justice, peace, and disarmament.

World War II brought with it several areas in the community where the Council saw a mission. Two major programs were the Armed Forces Ministry Service center, housed at the YMCA, which offered a "home away from home" for servicemen stationed in the Seattle area, and various Japanese-American support programs.

By 1957 confusion over the roles of the regional and local councils, and a high budget deficit prompted a self study. In 1959, following the recommendations of a study by the National Council of Churches (the Sanderson Field Survey Report), the existing organization was formally separated into two councils. Gertrude Apel resigned her position during this time (July 1958).

The two new councils were the Greater Seattle Council of Churches, headed by the Rev. Lemuel Petersen, and the Washington-Northern Idaho Council of Churches, headed by the Rev. Ralph Turnindge. The mission of the new Seattle council was to provide churches with an instrument for cooperative ministry to the larger community; it also provided leadership training and other services to local congregations.

A major effort for the new Seattle council was participation in the Seattle World's Fair (Century 21 Exposition) in the summer of 1962. Involvement included financing and administration for the "Christian Witness in Century 21" pavilion and a children's pavilion, which offered activities and childcare.

The 1960s also brought continued involvement in the socio-political areas of race relations, civil rights, and human service. In 1968 a Task Force for Redesign was appointed to recommend an administrative structure that could more efficiently "meet new and pressing urban problems." It was felt that the ability to address the problems of a rapidly growing urban community was hampered by the tradition-bound philosophy and departmental structure of the existing council.

In May 1969 the Greater Seattle Council of Churches celebrated 50 years of work in the community. At the close of the year, the organization was formally dissolved and replaced with the new Church Council of Greater Seattle. The new council was structured to be more flexible, with a short-term, task-focused orientation that was designed to review priorities, plan strategies, and mobilize resources to address the rapidly changing needs of the community. The emphasis shifted from aid to individual churches toward providing a forum for a concerted effort to combat major social problems.

Apart from the task forces of the council, which were designed to be flexible and changing, a subsidiary "Church Services Agency" was established to maintain such ongoing pastoral care programs as the Friend to Friend Nursing Home Visitation Program, the Chore Services Volunteer Program, and Hospital Chaplaincy and Youth Service Center Programs.

The Rev. William B. Cate became the president-director of the new organization and served until his retirement in 1990. The new council was immediately faced with a major challenge. Severe Boeing Aircraft Company layoffs threw the Seattle economy into a depression and left thousands of people hungry. The Neighbors in Need food bank program was developed by Seattle churches as a response to the crisis. The success of this program led to its replication in other communities.

In 1971 the council identified the promotion of peace as its second highest priority and experimented with a coalition task force made up of community peace organizations. The Seattle Ecumenical Religious Peace Action Coalition (SERPAC) was created as a vehicle to explore ways of continuing the momentum of Vietnam war protests. The coalition model proved very successful and SERPAC became the official peace task force of the council.