KJR (950 kHz) is an all-sports AM radio station owned by iHeartMedia in Seattle, Washington. KJR is the Puget Sound region's home of Fox Sports Radio and Infinity Sports Network, mostly carrying their national programming, while co-owned KJR-FM has local sports talk shows during the day and evening. KJR-AM-FM are the flagship stations for Seattle Kraken hockey. During the Seattle Seahawks season, the stations use the slogan "Home of the 12th Man". The studios are in Seattle's Belltown neighborhood northwest of downtown.

KJR is among the oldest radio stations in the United States, tracing its lineage back to an experimental station in 1920. It is powered at 50,000 watts, the maximum for commercial AM stations. It uses a directional antenna with a three-tower array to protect other stations on 950 AM from interference. The transmitter is on 105th Avenue SW on Vashon Island.

KJR's first formal broadcasting license was issued on March 9, 1922. However, the station's origin dates back to earlier broadcasts conducted by the station's first owner, Vincent I. Kraft.

Beginning in 1917, Kraft was the director of the local Y.M.C.A. School of Radio Telegraphy. In early 1920, he and O. A. Dodson organized the Northwest Radio Service Company. Details on Kraft's earliest broadcasting efforts are limited. However, in August of that year he began an irregular series of broadcasts originating from his Cowen Park home at 5503 14th Avenue, N.E. His amateur station had the call sign 7AC. Later that year Kraft was issued a license for an Experimental station, with the call sign 7XC. In early September 1921 he began transmitting programs on a regular schedule, three evenings a week from 7:45-8:30 p.m.

In early February 1922, Kraft built a radio transmitter used by a temporary station, KDP, to broadcast a week-long series of programs from Saint James' Cathedral. Following these broadcasts he began using the KDP transmitter at 7XC. On February 28, 1922, he resigned his Y.M.C.A. post in order to assume active management of Northwest Radio.

Initially there were no specific standards for stations making broadcasts intended for the general public, and radio stations holding a variety of license classes, most commonly Experimental and Amateur, began adopting regular broadcasting schedules. On December 1, 1921, the U.S. Department of Commerce, which regulated radio at this time, adopted a regulation formally establishing a broadcasting station category, which set aside the wavelength of 360 meters (833 kHz) for entertainment broadcasts, and 485 meters (619 kHz) for market and weather reports.

A few months later Kraft applied for one of the new broadcasting licenses, which was issued on March 9, 1922, with the randomly assigned call letters KJR, for operation on both 360 and 485 meters. It had been initially reported that the station's new call sign was "KAJR", however this turned out to be an error in a telegram sent by the Commerce Department, and shortly thereafter it was correctly reported that the assignment was actually "KJR". Later in 1922 KJR's licensee was changed to "Northwest Radio Service Co. (Vincent I. Kraft)".

KJR was the third license issued for a Seattle broadcasting station, preceded by KFC (Northern Radio & Electric, licensed December 8, 1921, and deleted January 23, 1923) and KHQ (Louis Wasmer, licensed February 28, 1922, moved to Spokane in 1927–now KQNT). Despite this, KJR claims to have the oldest broadcasting lineage in Seattle by claiming 7XC as part of its history.