The O. K. Palmer House is the historic home of Osmer K. Palmer and is located in Chehalis, Washington. The building was listed on the National Register of Historic Places (NRHP) in 1986 and is situated in the city's NRHP-listed Pennsylvania Avenue-West Side Historic District.

Osmer K. Palmer and his wife purchased the property, which had an existing home, in 1908 from Mr. and Mrs. Jacob Miller. Palmer rebuilt the historic home beginning in 1910 and was near completion by the end of 1911. The construction costs were recorded as $6,000. The Palmers expanded the lot after purchasing an adjoining parcel at the Pennsylvania-Folsom intersection in 1920. Four years later in 1924, Palmer traded the entire parcel and home to T.J. Long, for the Long's house further down Pennsylvania Avenue.

The house won a $5 third-place prize in the 1927 Chehalis Better Home Premises contest. A renovation, done by homeowners at the time, was completed in 1999.

Osmer Palmer was born in Indiana in 1872, arriving from Tennessee to Chehalis in 1906. He owned a catalogue-based, pre-built home business, expanding it in 1919. He founded the Palmer Lumber and Manufacturing Company in Chehalis in 1908. The lumber company factory burned down in 1911 but Palmer had it rebuilt the following year, enlarging the footprint in 1925. As of 2023, the company remains in existence.

Palmer served as a school board director for the Chehalis School District, and during the Great War, was chairman of the Chehalis Council of Defense.

The Palmers had three children. His only son, Leon, while attending an aviation training camp as an enlisted student, died of pneumonia in 1918. Osmer Palmer died in 1952.

The home is a 2+1⁄2 story, American Foursquare style residential structure. Following standard Foursquare design, the house rests upon a squared, sandstone foundation and contains a basement. The Palmer House contains a large front porch with several broad pillars. Other features include bay windows, a hipped roof and dormers, and distended eaves.

The house was officially accepted to the NRHP list on May 15, 1986. As of 2023, the Palmer House was one of eleven NRHP sites in the city of Chehalis.

The O.K. Palmer House was awarded recognition as a historic, renovated home by the city of Chehalis via its Chehalis Historic Preservation Commission. The accolade, given in 2006, lists the home as a crucial part of the history of the city and a plaque, denoting the original build and important restoration dates, is displayed on the house.

• O. B. McFadden House

• City of Chehalis National Register Sites
• Revisiting Washington - Chehalis