Eastgate is located south of exit 11-A along I-90, which runs east-west along Eastgate's north side. Issaquah is to the east along I-90, and I-405 is a short distance to the west. Much of Eastgate is on the northwest flank of Cougar Mountain. Immediately to the west is Factoria. Immediately to the south is Somerset. To the north is the I-90 Corridor. According to the United States Census Bureau, the CDP has a total area of 1.3 square miles (3.3 km2), all of it land.