Duke President Richard H. Brodhead calls Winfrey one of the most compelling figures of this time, pointing to her work as both an entertainer and a philanthropist.
Watch Oprah's entire speech to Duke's class of 2009
"You really haven't completed the circle of success unless you can help somebody else move forward, Winfrey said."That's the truth!"
The university awarded more than 4,400 undergraduate, graduate and professional degrees. Winfrey also received an honorary doctor of humane letters degree. Her godson, Gayle King's child, is also part of the Blue Devil class of 2009.
Some of the graduates say they already have jobs, but Winfrey urged them to go further.
"Graduates, I know this," Winfrey said."If you can see the possibility of change in your life, see the possibility of what you can become and not just what you are, you will be a huge success."
She talked about people she's had on her show who improved their lives through good deeds for others.
"You never know what kindness you offer today to someone, how that might live with them forever," she said. "So graduates, if you can be generous enough to say kind, affirming words to those who long to hear them, you will be a huge success."
And that theme of committing to some kind of public service and reaching back really resonated with some of the graduates.
"It brought tears to my eyes! I really loved it. It set the tone so well, I think, for the day." Mary Via said.
They all say they are inspired by Winfrey's appearance.
"She did a great job of bringing together a message to give back to the community," Caroline Buyer said.