Dodd, whose personable style won him friends in both parties, noted it is common for retiring senators to say they will miss the people, but not the work.
"You won't hear that from me," he said. "Most assuredly I will miss the people of the Senate. But I will miss the work, as well."
Dodd thanked the people of Connecticut for his three decades in the Senate. He is the state's longest serving senator.
"I owe an enormous debt of gratitude to the people of Connecticut whose confidence, patience, and spirit has given my life and its work meaning," Dodd said.
Dodd drew hugs, a few tears and praise from colleagues on the crowded Senate floor, a departure from the chamber's usual formality, as his wife and two young daughters looked on from the gallery.
Speaking as the lame duck session of Congress wraps up, Dodd bemoaned the corrosive power of big money in Congress.
"Our electoral system is a mess," he said. "Powerful financial interests, free to throw money about with little transparency, have corrupted the basic principles underlying our representative democracy. And, as a result, our political system at the federal level is completely dysfunctional."
Dodd, 66, announced in January that he would not seek a sixth term. At the time, he was trailing former Republican Congressman Rob Simmons in the polls.
His political stock fell in recent years with a controversy involving low-rate mortgages he received under a VIP program, charges that he was too cozy with Wall Street interests and his failed 2008 presidential bid, which did not play well in his home state. Dodd moved his family to Iowa several weeks before the caucuses there.
The mortgage controversy dogged him for months. The Senate ethics panel cleared him of breaking rules by getting the mortgages but scolded him for not doing more to avoid the appearance of sweetheart deals. Dodd insisted the rates he received were available to other consumers with good credit.
He serves as chairman of the Senate Banking panel and has been front and center in some of the biggest fights on Capitol Hill in recent years. The committee was at the center of efforts to stop the economic meltdown, and Dodd played a prominent role in the debate over health care, taking over for Sen. Edward Kennedy during his illness and after his death in 2009.
Dodd has said that losing a sister and Kennedy, his longtime close friend, factored into his decision to retire. Dodd himself was diagnosed with prostate cancer during the summer of 2009.
Richard Blumenthal, Connecticut's longtime attorney general, will keep the seat in Democratic control when he takes over for Dodd next year.
Dodd, who also served three terms in the House, plans a farewell tour across Connecticut next month to thank supporters.
Dodd has not said what he plans to do once he leaves the Senate.
The New York Times has reported that he is among the candidates being considered to head the Motion Picture Association of America.