Born in Everett, Washington, Jackson went on to graduate with a Bachelor's degree from Stanford University and a law degree from the University of Washington. In 1935 (the year of his law school graduation) he was admitted to the bar and began to practice law in Everett. He found immediate success, and was the prosecuting attorney for Snohomish County from 1938 to 1940.
His involvement in politics grew from there; he successfully ran for Congress as a Democrat in 1940 and took his seat in the House of Representatives with the Seventy-Seventh Congress on January 3, 1941. From that date forward, Jackson would not lose a congressional election. He attended the International Maritime Conference in Copenhagen, Denmark in 1945 with the American delegation, and was elected president of the same conference in 1946, when it was held in Seattle, Washington. From 1945 to 1947, Jackson was also the chairman of the Committee on Indian Affairs. In the 1952 election, Jackson relinquished his seat in the House for a run at one of Washington's Senate seats -- he won that election, and remained a Senator for thirty years. In 1963, Jackson was made chairman of the Committee on Interior and Insular Affairs, a post he would hold until 1979. From 1977 until 1981, Jackson was chairman of the Committee on Energy and Natural Resources.
Jackson was not only successful as a politician in Washington State, but also found recognition on the national level, rising to the position of chairman of the Democratic National Committee in 1960. He would not achieve the party's ultimate honor, however, as he was denied the Democratic nomination for President despite two attempts at it, in 1972 and 1976.
Jackson died in 1983 in Everett, and is buried in Evergreen Cemetery in that city. He continues to be thought of by most citizens of Washington State as one of their greatest statesmen, and the University of Washington has named the Jackson School of International Studies in his honor. The US Navy submarine Henry M. Jackson was also named after him, in recognition of his longtime support of the nation's military.