The first Spanish and British explorations into this region in the 17th and 18th centuries reported large, well-established communities of natives living here. Native Americans have roamed, lived and fished the coastal waters of Western Washington and British Columbia for at least 10,000 years.

The name "Semiahmoo" translates as "half-moon" a term that perfectly describes the curving coastline of the bay.

Semiahmoo Resort is built on the site of a historic salmon-packing cannery. Salmon were packed here until 1965 and labeling of packed salmon continued until 1974.

Integrating the existing structure into its building design, Semiahmoo Resort opened its doors in 1987 as Washington’s largest full-service destination resort. The Semiahmoo Golf Course, designed by Arnold Palmer, opened a year earlier in 1986 and is a three-time recipient of the Golf Magazine Silver Award for Best Golf Resorts in America. It was also rated the number one public course in Washington by Golf Digest Magazine in its May 2003 issue. Semiahmoo resort is a participant in the Audubon Cooperative Sanctuary program.

Loomis Trail Golf Club was acquired by Semiahmoo Resort to bring its golf offerings to 36 holes of championship golf. Loomis Trail received the number two rated public golf course in Washington by Golf Digest Magazine.

In 2003, Skagit Valley Casino Resort became the sole managing partner of Semiahmoo Resort, bringing many years of successful management experience to the four-diamond property.