In 1967, the position of City Planner was created by amendment of the City Charter. The post was directly responsible to the Mayor and attached to the City Planning Commission, a semi-professional advisory body concerned with developing current and long-range planning policy. From 1967 to 1969, the reorganized Commission, now with significantly expanded research and design capabilities, would be referred to as the Planning Department. The Planning Commission continued to operate much as before, though now within the larger Department structure. The Department was absorbed into the new Department of Community Development (DCD) in 1969, becoming the Planning Division.

In 1972, the Office of Executive Policy (OEP) was established as part of the Executive Departments Model Cities program, and in 1973 it was moved to the same departments Administration of City Operations Program. The OEPs area of responsibility was staff support for policy development within the Executive Department as a whole. In 1973, the Executive Departments Intergovernmental Affairs Office (IGA) was incorporated into the OEP, establishing a mixed mission of policy planning, issue analysis, liaison with local, regional, tribal, international, and extra-jurisdictional organizations, and lobbying for City interests during the State legislative session.

In 1974, the Office of Policy Planning (OPP) was established within the Executive Department with the purpose of centralizing and systematizing the planning of Seattles physical and social development. This organization was formed from the OEP, to which was transferred policy functions from a number of offices and departments, including Grants Management from the Office of Management and Budget (OMB), the Planning and Programming and Economic Development Programs from DCD, and all Comprehensive Policy Plan development efforts heretofore undertaken by individual City departments. As the department most affected by this reorganization, the DCD would lose city-wide policy planning functions and become primarily concerned with program development and administration.

OPP was designed with two principal divisions, Policy Management and Policy Development. The Law and Justice Planning division was added in 1975, and tasked with crime analysis and preventative planning. The OEPs Intergovernmental Affairs Office remained part of the Administration of City Operations program until 1975, when it was incorporated into the OPPs Intergovernmental Relations Division. In this guise and as an independent agency by 1979, Intergovernmental Affairs represented and promoted City policy to federal, state, regional, local, tribal and international governments. It also acted as Seattles lobbyist during the States legislative sessions.

In 1979, the OPP was converted into the Office of Policy and Evaluation (OPE), once again under the purview of the Executive Department. The new offices mandate was to oversee City planning, evaluation, and policy development activities. The main structural alterations were the removal of the Law and Justice Planning and Intergovernmental Affairs divisions and their subsequent elevation to Office-level positions within the same department. In addition, significant responsibilities and staff assets related to planning were transferred to DCD, including economic data analysis, housing, and citizen participation. The OPE was organized into three divisions: Policy Coordination and Management, Growth Management (changed to Special Policy Development Projects in 1980), and Urban Development and Issues (changed to Policy Analysis and Evaluation in 1980).

In 1982, the Land Use and Transportation Project (LUTP) was formed from those assets of the OPE relating to planning and policy development for land use, transit and transportation, housing, and related economic development. Other OPE functions and personnel, chiefly in the form of the Policy Coordination and Management division, became part of OMB. Among the LUTPs duties was the generation of the Comprehensive Land Use Policies Plan, a comprehensive set of policy guidelines begun in 1978 and finally completed in 1986.

In 1986 the LUTP was consolidated into a new organization, the Office for Long-Range Planning (OLP). This new entity would be part of a general Planning Program within the Executive Department, along with the newly-formed Office of Strategic Human Services Planning (OSHSP), which would be responsible for human services needs assessment and related policy planning. In addition to LUTPs existing functions, the OLP was tasked with coordinating City policy for physical development, the environment and transportation; establishing a centralized planning database, and conducting long-range planning on issues deemed high- priority by the Mayor and the City Council. By 1989, the OLP was also assigned the job of administering effective City participation in regional planning initiatives, on topics like hazardous waste disposal and public transit.

In 1992 the OLP and OSHSP were combined to create the new Planning Department, marking the first point since 1969 that planning and policy development for the City fell outside the direct control of the Executive Department. In addition to cultivating policy on land use, transportation, housing, the environment, human services, and urban design, the Planning Departments stated mission included the pursuit of local/regional planning collaboration as well as the evaluation of city policies for compliance with Washingtons Growth Management Act and Seattles Comprehensive Plan Framework Policies. The department was segmented into four divisions: Comprehensive Planning, Urban Research, Strategic and Special Projects, and Administrative.

In 1995 the Office of Management and Planning (OMP) was created by bringing together the Office of Management and Budget and Planning Department. OMP was the lead office within the Executive Department for community planning, budgeting, capital infrastructure analysis, forecasting, policy and economic analysis, and management.

In early 1998, the Mayor divided the OMP and formed a new Strategic Planning Office (SPO) for policy planning in the Executive Department. The Citys budget function was reorganized in the newly- formed City Budget Office (CBO), located in the Executive Services Department.

In 2002 the Strategic Planning Office was abolished and its functions were provided in other executive agencies, namely the Department of Design, Construction and Land Use; Department of Transportation; Department of Neighborhoods; Department of Finance, and Office of Economic Development. Certain former SPO functions related to policy development, inter-department policy coordination, and planning support for the Mayor and City Council were moved to a new Office of Policy and Management (OPM). In 2009, the OPM was itself abolished, with the balance of its budget, staff, and functions folded into the Office of the Mayor.

In 2015, a new Office of Planning and Community Development (OPCD) was spun off from the Department of Planning and Development. Its mission was to facilitate and support comprehensive planning for the city's future growth and development.