The department is responsible for services in the communities of Carnation, Issaquah, North Bend, Preston, Sammamish, Tiger Mountain and Wilderness Rim.

[1] In total, Eastside Fire & Rescue's service area is 190 square miles (490 km2) with a population of over 120,000.

These municipalities use an Interlocal Agreement to establish how Eastside Fire & Rescue operates.

Participating cities are Carnation, Issaquah, North Bend, Preston, Sammamish, Tiger Mountain, Woodinville, and Wilderness Rim.

The consolidation was prompted by the municipalities' desire to provide better fire protection and emergency medical services to the general public in a cost-effective manner.