Vice President Joe Biden attended the hour-long event Thursday and praised Dingell's efforts to fight for the middle class.
Congressional leaders also unveiled a portrait of Dingell as a gift to him from the House.
Dingell, who tallied his 20,997th day on Capitol Hill last week, spoke at the ceremony and pressed for more civility in Washington.
"I'm troubled about the times in which we find ourselves," Dingell said. "Congress means 'a coming together,' where people come together to work for great causes in which they all have an important interest. We have, I think, unfortunately, because of the pressure of the times, forgotten this."
Dingell, a 30-term Democrat from Michigan, also spoke of his father, John Dingell Sr., another long-serving congressman.
"He fought for something of particular concern: social justice. He left me an example, and he was a great teacher," Dingell said.