Robert Irwin said on "The Tonight Show" that he will be walking his sister Bindi Irwin down aisle on her wedding day. "I'm walking Bindi down the aisle, which will be awesome," Robert said on Thursday to host Jimmy Fallon. Bindi, 21, became engaged to her boyfriend Chandler Powell, 22, in July. Robert and Bindi are the children of late Crocodile Hunter star Steve Irwin. The siblings appear on Animal Planet's "Crikey! It's the Irwins" alongside their mother Terri. Robert also explained how he took the photo of Powell getting down on one knee to propose to Bindi at the Australia Zoo. Robert had rehearsed the photo earlier, standing in for Bindi. "It was the happiest moment of my life," he joked about Powell getting down on one knee for him in the rehearsal photo. Robert, 15, praised Powell and mentioned that the professional wakeboarder asked him and his mother's permission to propose to Bindi. "He's the loveliest guy," the television star said. "He's so loyal and so kind to Bindi." "Crikey! It's the Irwins" will return for Season 2 on Oct. 5.