He currently serves as the top Democrat on the House Education and the Workforce Committee and is the fifth most senior member of the U.S. House.
Miller, 68, first came to Congress in 1974 at the age of 29.
"I'm proud of what I have been able to accomplish on behalf of children, working people and the environment, in my district and for our country, especially passage of national health care reform," he said Monday in a statement.
"I have not won every fight that I have waged. And there remain, of course, many critical challenges waiting to be addressed. But I have no regrets about what I have accomplished and what I have tried to accomplish in the public interest. Now, I look forward to one last year in Congress fighting the good fight and then working in new venues on the issues that have inspired me, and I will not seek re-election this fall. What a wonderful experience this has been."
The Nation magazine recently named Miller the 2013 "Most Valuable Member of the House" for his work on the minimum wage, food stamps, garment worker safety, and fair trade policy.
He has served as chair of the Select Committee on Children, Youth and Families, the Committee on Natural Resources, the Committee on Education and Labor and was the long-time co-chair of the Democratic Steering and Policy Committee.