Washington was admitted to the Union on November 11, 1889, and elects its United States senators to class 1 and class 3. Its current U.S. senators are Democrats Patty Murray (since 1993) and Maria Cantwell (since 2001) making it one of only four states alongside Minnesota, Nevada and New Hampshire to have two female U.S. senators. Warren Magnuson was Washington's longest-serving senator (1944–1981).
|- style="height:2em"| colspan=3 | Vacant| nowrap | Nov 11, 1889 –
Nov 20, 1889| Washington elected its first senators after it was admitted to the Union.| rowspan=3 | 1| rowspan=2 | rowspan=2 | 1| Washington elected its first senators after it was admitted to the Union.| nowrap | Nov 11, 1889 –
Nov 20, 1889| colspan=3 | Vacant
|- style="height:2em"! rowspan=2 | 1| rowspan=2 align=left |
John B. Allen| rowspan=2 | Republican| rowspan=2 nowrap | Nov 20, 1889 –
Mar 3, 1893| rowspan=2 | Elected in 1889.Legislature failed to re-elect.| Elected in 1889.| rowspan=5 nowrap | Nov 20, 1889 –
Mar 3, 1897| rowspan=5 | Republican| rowspan=5 align=right |
Watson C. Squire! rowspan=5 | 1
|- style="height:2em"| | rowspan=4 | 2| rowspan=4 | Re-elected in 1891.Lost re-election.
|- style="height:2em"| colspan=3 | Vacant| nowrap | Mar 4, 1893 –
Feb 19, 1895| Legislature failed to elect. The governor appointed John Allen, but the Senate rejected his credentials.| rowspan=4 | 2| rowspan=2
|- style="height:2em"! rowspan=3 | 2| rowspan=3 align=left |
John L. Wilson| rowspan=3 | Republican| rowspan=3 nowrap | Feb 19, 1895 –
Mar 3, 1899| rowspan=3 | Elected in 1895 to finish the vacant term, but took his seat late.Lost renomination.
|- style="height:2em"|
|- style="height:2em"| | rowspan=3 | 3| rowspan=3 | Elected in 1897.[1] Lost re-election.[2] | rowspan=3 nowrap | Mar 4, 1897 –
Mar 3, 1903| rowspan=3 | Democratic| rowspan=3 align=right |
George Turner! rowspan=3 | 2
|- style="height:2em"! rowspan=3 | 3| rowspan=3 align=left |
Addison G. Foster| rowspan=3 | Republican| rowspan=3 nowrap | Mar 4, 1899 –
Mar 3, 1905| rowspan=3 | Elected in 1899.[3] Retired.| rowspan=3 | 3|
|- style="height:2em"|
|- style="height:2em"| | rowspan=3 | 4| rowspan=3 | Elected in 1903.[2] Lost renomination.| rowspan=3 nowrap | Mar 4, 1903 –
Mar 3, 1909| rowspan=3 | Republican| rowspan=3 align=right |
Levi Ankeny! rowspan=3 | 3
|- style="height:2em"! rowspan=3 | 4| rowspan=3 align=left |
Samuel H. Piles| rowspan=3 | Republican| rowspan=3 nowrap | Mar 4, 1905 –
Mar 3, 1911| rowspan=3 | Elected in 1905.[4] Retired.| rowspan=3 | 4|
|- style="height:2em"|
|- style="height:2em"| | rowspan=3 | 5| rowspan=3 | Elected in 1909.| rowspan=12 nowrap | Mar 4, 1909 –
Nov 19, 1932| rowspan=12 | Republican| rowspan=12 align=right |
Wesley L. Jones! rowspan=12 | 4
|- style="height:2em"! rowspan=6 | 5| rowspan=6 align=left |
Miles Poindexter| | Republican| rowspan=6 nowrap | Mar 4, 1911 –
Mar 3, 1923| rowspan=3 | Elected in 1911.| rowspan=3 | 5|
|- style="height:2em"| | Progressive|
|- style="height:2em"| rowspan=4 | Republican| | rowspan=3 | 6| rowspan=3 | Re-elected in 1914.
|- style="height:2em"| rowspan=3 | Re-elected in 1916.Lost re-election.| rowspan=3 | 6|
|- style="height:2em"|
|- style="height:2em"| | rowspan=3 | 7| rowspan=3 | Re-elected in 1920.
|- style="height:2em"! rowspan=8 | 6| rowspan=8 align=left |
Clarence Dill| rowspan=8 | Democratic| rowspan=8 nowrap | Mar 4, 1923 –
Jan 3, 1935| rowspan=3 | Elected in 1922.| rowspan=3 | 7|
|- style="height:2em"|
|- style="height:2em"| | rowspan=5 | 8| rowspan=3 | Re-elected in 1926.Died, having already lost re-election.
|- style="height:2em"| rowspan=5 | Re-elected in 1928.Retired.| rowspan=5 | 8|
|- style="height:2em"| rowspan=3
|- style="height:2em"| | nowrap | Nov 19, 1932 –
Nov 22, 1932| colspan=3 | Vacant
|- style="height:2em"| Appointed to finish Jones's term.Retired.| nowrap | Nov 22, 1932 –
Mar 3, 1933| | Republican| align=right |
Elijah S. Grammer! 5
|- style="height:2em"| | rowspan=3 | 9| rowspan=3 | Elected in 1932.| rowspan=8 nowrap | Mar 4, 1933 –
Nov 13, 1944| rowspan=8 | Democratic| rowspan=8 align=right |
Homer Bone! rowspan=8 | 6
|- style="height:2em"! rowspan=3 | 7| rowspan=3 align=left |
Lewis B. Schwellenbach| rowspan=3 | Democratic| rowspan=3 nowrap | Jan 3, 1935 –
Dec 16, 1940| rowspan=3 | Elected in 1934.Resigned.| rowspan=5 | 9|
|- style="height:2em"|
|- style="height:2em"| rowspan=3 | rowspan=7 | 10| rowspan=5 | Re-elected in 1938.Resigned to become Judge on the United States Court of Appeals for the Ninth Circuit.
|- style="height:2em"| colspan=3 | Vacant| nowrap | Dec 16, 1940 –
Dec 19, 1940|
|- style="height:2em"! rowspan=6 | 8| rowspan=6 align=left |
Monrad Wallgren| rowspan=6 | Democratic| rowspan=6 nowrap | Dec 19, 1940 –
Jan 9, 1945| Appointed to finish Schwellenbach's term, having already been elected to the next term.
|- style="height:2em"| rowspan=5 | Elected in 1940.Resigned.| rowspan=7 | 10|
|- style="height:2em"| rowspan=3
|- style="height:2em"| | nowrap | Nov 13, 1944 –
Dec 14, 1944| colspan=3 | Vacant
|- style="height:2em"| Appointed to finish Bone's term, having already been elected to the next term.| rowspan=21 nowrap | Dec 14, 1944 –
Jan 3, 1981| rowspan=21 | Democratic| rowspan=21 align=right |
Warren Magnuson! rowspan=21 | 7
|- style="height:2em"| rowspan=3 | rowspan=5 | 11| rowspan=5 | Elected in 1944.
|- style="height:2em"! 9| align=left |
Hugh Mitchell| | Democratic| nowrap | Jan 10, 1945 –
Dec 25, 1946| Appointed to finish Wallgren's term.Lost election to next term and resigned.
|- style="height:2em"! rowspan=4 | 10| rowspan=4 align=left |
Harry P. Cain| rowspan=4 | Republican| rowspan=4 nowrap | Dec 26, 1946 –
Jan 3, 1953| Appointed to finish Wallgren's term, having already been elected to the next term.
|- style="height:2em"| rowspan=3 | Elected in 1946.Lost re-election.| rowspan=3 | 11|
|- style="height:2em"|
|- style="height:2em"| | rowspan=3 | 12| rowspan=3 | Re-elected in 1950.
|- style="height:2em"! rowspan=16 | 11| rowspan=16 align=left |
Henry M. Jackson| rowspan=16 | Democratic| rowspan=16 nowrap | Jan 3, 1953 –
Sep 1, 1983| rowspan=3 | Elected in 1952.| rowspan=3 | 12|
|- style="height:2em"|
|- style="height:2em"| | rowspan=3 | 13| rowspan=3 | Re-elected in 1956.
|- style="height:2em"| rowspan=3 | Re-elected in 1958.| rowspan=3 | 13|
|- style="height:2em"|
|- style="height:2em"| | rowspan=3 | 14| rowspan=3 | Re-elected in 1962.
|- style="height:2em"| rowspan=3 | Re-elected in 1964.| rowspan=3 | 14|
|- style="height:2em"|
|- style="height:2em"| | rowspan=3 | 15| rowspan=3 | Re-elected in 1968.
|- style="height:2em"| rowspan=3 | Re-elected in 1970.| rowspan=3 | 15|
|- style="height:2em"|
|- style="height:2em"| | rowspan=3 | 16| rowspan=3 | Re-elected in 1974.Lost re-election.
|- style="height:2em"| rowspan=3 | Re-elected in 1976.| rowspan=3 | 16|
|- style="height:2em"|
|- style="height:2em"| | rowspan=5 | 17| rowspan=5 | Elected in 1980.Lost re-election.| rowspan=5 nowrap | Jan 3, 1981 –
Jan 3, 1987| rowspan=5 | Republican| rowspan=5 align=right |
Slade Gorton! rowspan=5 | 8
|- style="height:2em"| Re-elected in 1982.Died.| rowspan=5 | 17| rowspan=3
|- style="height:2em"| colspan=3 | Vacant| nowrap | Sep 1, 1983 –
Sep 8, 1983|
|- style="height:2em"! rowspan=3 | 12| rowspan=3 align=left |
Daniel J. Evans| rowspan=3 | Republican| rowspan=3 nowrap | Sep 8, 1983 –
Jan 3, 1989| rowspan=3 | Appointed to continue Jackson's term.Elected to finish Jackson's term.Retired.
|- style="height:2em"|
|- style="height:2em"| | rowspan=3 | 18| rowspan=3 | Elected in 1986.Retired.| rowspan=3 nowrap | Jan 3, 1987 –
Jan 3, 1993| rowspan=3 | Democratic| rowspan=3 align=right |
Brock Adams! rowspan=3 | 9
|- style="height:2em"! rowspan=6 | 13| rowspan=6 align=left |
Slade Gorton| rowspan=6 | Republican| rowspan=6 nowrap | Jan 3, 1989 –
Jan 3, 2001| rowspan=3 | Elected in 1988.| rowspan=3 | 18|
|- style="height:2em"|
|- style="height:2em"| | rowspan=3 | 19| rowspan=3 | Elected in 1992.| rowspan=18 nowrap | Jan 3, 1993 –
present| rowspan=18 | Democratic| rowspan=18 align=right |
Patty Murray! rowspan=18 | 10
|- style="height:2em"| rowspan=3 | Re-elected in 1994.Lost re-election.| rowspan=3 | 19|
|- style="height:2em"|
|- style="height:2em"| | rowspan=3 | 20| rowspan=3 | Re-elected in 1998.
|- style="height:2em"! rowspan=12 | 14| rowspan=12 align=left |
Maria Cantwell| rowspan=12 | Democratic| rowspan=12 nowrap | Jan 3, 2001 –
present| rowspan=3 | Elected in 2000.| rowspan=3 | 20|
|- style="height:2em"|
|- style="height:2em"| | rowspan=3 | 21| rowspan=3 | Re-elected in 2004.
|- style="height:2em"| rowspan=3 | Re-elected in 2006.| rowspan=3 | 21|
|- style="height:2em"|
|- style="height:2em"| | rowspan=3 | 22| rowspan=3 | Re-elected in 2010.
|- style="height:2em"| rowspan=3 | Re-elected in 2012.| rowspan=3 | 22|
|- style="height:2em"|
|- style="height:2em"| | rowspan=3 | 23| rowspan=3 | Re-elected in 2016.
|- style="height:2em"| rowspan=3 | Re-elected in 2018.| rowspan=3 | 23|
|- style="height:2em"|
|- style="height:2em"| | rowspan=3 | 24| rowspan=3 | Re-elected in 2022.
|- style="height:2em"| rowspan=3 colspan=5 | To be determined in the 2024 election.| rowspan=3| 24|
|- style="height:2em"|
|- style="height:2em"| | 25| colspan=5 | To be determined in the 2028 election.