Montesano was first settled in 1852 by Isaiah L. Scammon. in 1860 the county seat of what was then called Chehalis County was moved to "the place of J.L. Scammons". Mrs. Lorinda Scammon was very religious and wished to have the place named Mount Zion. Another early settler, Samuel James, suggested "Montesano" as having a more pleasant sound and meaning about the same. The suggestion was approved and soon after, a post office was secured with the name Montesano.

Montesano serves as the county seat for Grays Harbor County. The city is also the halfway point between Olympia and the ocean beaches. There are many other things to do in and around the area. Montesano also serves as a hub for many outdoor activities, including camping, fishing, hunting, kayaking, boating, hiking, and bird watching. A prominent feature of the town is the 1911 Grays Harbor County Courthouse. This is a three-story structure with a domed tower. The interior features murals of local history. Montesano maintains a sense of community. Montesano neighborhoods range from historic to contemporary homes, homes with a lot of character and charm, and even homes on acreage, all within the city limits.