Bidding for the bike closed on the eBay auction Web site at 5 p.m. Thursday, and Leno announced during the taping of Thursday's "Tonight Show" that the winning bid was $505,100.
Ninety-five percent of the winning bid will be donated to the American Red Cross for Katrina relief efforts.
For the past four weeks, "Tonight Show" guests and surprise arrivals have been autographing the Harley-Davidson motorcycle.
The final signers on Thursday were guests Matthew McConaughey and Angie Harmon and surprise walk-ons Jimmy Smits and Jennifer Love Hewitt.
Previous signers include Gov. Arnold Schwarzenegger, Billy Crystal, Reese Witherspoon, Adam Sandler, Jennifer Garner and Pamela Anderson.
Leno's is the one of the latest of celebrities chipping in for hurricane relief. Earlier this months, CBS, ABC, FOX, NBC, The WB, PBS and a score of other stations, broadcast a concert: "" including artists Sheryl Crow, the Dixie Chicks, Alicia Keys, Randy Newman, Paul Simon, Rod Stewart and Neil Young. The concert was broadcast in more than 100 countries.
Another big concert in New York City drew a range of celebrity performers, including former president Clinton, who briefly took the stage, but not to sing. Elton John, Simon and Garfunkel, Bette Midler, Diana Krall and Lenny Kravitz, Dave Matthews, Tom Waits, Trey Anastasio, John Meyer, along with New Orleans fixtures Ry Cooder, Buckwheat Zydeco, Irma Thomas and the Neville Brothers all performed at Madison Square Garden.
Some efforts, like Leno's, are more quirky.