Kirkland is an affluent city in King County, Washington, United States. It is a suburb of Seattle located on the Eastside (of Lake Washington). As of April 1, 2005, the city had an estimated population of 45,740, making Kirkland the eighth largest city in King County and the eighteenth largest city in the State.

Notable features of the city include its downtown, located on the lakefront (Kirkland is the only city on the Eastside with a waterfront downtown), with many restaurants and art galleries and a 400 seat performing arts center; numerous public parks, including a number of beaches; and a large collection of public art, primarily bronze sculptures.

Kirkland is the home of the Seattle Seahawks training facility. Warehouse chain Costco previously had its headquarters in Kirkland (now in Issaquah), hence the "Kirkland Signature" store brand. Several prominent companies like Bungie Studios (developer of the Halo, Marathon, Myth and Oni video game series) have headquarters in Kirkland; see List of companies based in Kirkland, Washington. It is also home to a Google development office, and serves as a home for many Microsoft and Amazon.com employees.

Kirkland had its moment in the limelight when the 1982 Kirkland National Little League team won the Little League World Series. It also was the home to Little League's 1992 Big League Softball World Series Champions Representing the Eastside District Nine Leagues. Since 1999 Kirkland has been the home of the Little League Junior Softball World Series held each August at Kirkland's Everest Park.

Kirkland is known for its per capita income and its real estate market, which are both regularly among the very highest in the state. Based on per capita income, one of the more reliable measures of affluence, Kirkland ranks 13th of 522 areas in the state of Washington to be ranked.