In 1980, the independent office of the Planning Commission was established by ordinance. The Commission is made up of 15 Seattle citizens. The Commission's previous planning functions of reviewing site-specific applications and permits were transferred to the Department of Community Development. The Commission was given increased authority to address planning policies early in development stage instead of after policies are adopted. The mission of the new Planning Commission is to improve citizen participation and provide opportunities for public involvement on planning issues. The Commission is responsible for studying planning issues, carrying out public involvement activities, and developing recommendations for executive and legislative consideration. The Commission is also tasked with ensuring the application of the City's Comprehensive Plan principles.

In 2002, the Planning Commission became a part of the Department of Design, Construction and Land Use, which is now the Department of Planning and Development. In 2006, the Commission appointments were altered so that seven members are appointed by the Mayor and seven members are appointed by the City Council. The fifteenth member is appointed by the Commission.