Phelps, 23, was involved in seven world records -- some of the performances came as part of relay teams -- in the 2008 Summer Games in Beijing and has collected a record 14 gold medals in his career.

He is the first swimmer to win the honor. His eight gold medals in one Olympics broke the record set by Mark Spitz in 1972. Tennis star Billy Jean King was selected the Sportswoman of the Year over Spitz.

"Michael Phelps as the 2008 Sportsman of the Year was the easiest choice I have made," said Sports Illustrated Group Editor Terry McDonell in a news release Tuesday. "It is so obvious that he changed not only swimming but also the entire Olympic landscape."

Sports Illustrated said its award is presented annually to the person or team who transcended the year in both athletic performance and character.