Horn "methodically" walked about 100 yards into the Thursday evening performance of "Avenue Q" at the Wynn Las Vegas resort, said Bernie Yuman, longtime manager of the "Siegfried & Roy" show.
He was accompanied by his partner, Siegfried Fischbacher, and casino mogul Steve Wynn.
Horn, 60, has been walking without the aid of a rolling walker after months of six- to eight-hour days in physical rehabilitation, Yuman said. His injuries included a damaged neck artery and a crushed windpipe.
He has made other public appearances in recent months.
Horn was partially paralyzed when a 380-pound white tiger attacked him and dragged him by the neck during a performance of the "Siegfried & Roy" show at The Mirage resort.
The mauling ended the long-running "Siegfried & Roy" production, one of the most successful shows in Las Vegas history.
Yuman said Friday that Horn and some friends were preparing to mark Horn's 61st birthday on Oct. 3 — the second anniversary of the attack. He declined to provide details.
"We're going to continue to celebrate his birthday and his life," Yuman said, emphasizing the inspirational elements of Horn overcoming adversity.
"We look forward to Oct. 3 as we always have, but now it has new meaning," he said.