Addressing about 5,000 graduates at the Ivy League school in Philadelphia, the Oscar- and Tony-winning actor said the ceremony was "a little overwhelming and out of my comfort zone," which he said is why he accepted the invitation to speak.
"I had to come exactly because I might make a fool of myself," said Washington. "I've found that nothing in life is worthwhile unless you take risks. Nothing."
The 56-year-old star of "Malcolm X" and "Philadelphia" delivered a humorous speech with a sobering truth: Failure is inevitable. Yet instead of having something to fall back on, he said, graduates should "fall forward" - learn from their mistakes and keep going.
"Do you have the guts to fail?" Washington said. "If you don't fail, you're not even trying."
Washington also received an honorary doctorate at the ceremony. In granting the degree, Penn President Amy Gutmann said that his moving performances have "entertained us, inspired us and often enlightened us."
The Associated Press contributed to this report.