The Australian actor, 42, flew on a zip-line cable from the top sail of the famous landmark down to the stage, but hit the brakes too late, flipped up into a lighting rig and injured his right eye.
Winfrey immediately called for a break in filming, as paramedics rushed to the stage – but the injury was minor, and PEOPLE's Sexiest Man Alive 2008 was able to continue with his appearance after being tended to.
"That's gonna swell," said Winfrey, 56, as Jackman returned with a small piece of tape under his eye and a visible bruise beneath it. The actor then headed down into the front row to comfort his son, Oscar, 10, who was upset by the accident.
"That was so much fun until the end," he said. Referring the Winfrey's previous guest, he added with a laugh: "Bono was meant to do this, but they couldn't afford the insurance."
Jackman was at pains to make clear it was not the stunt team's fault. He had had a successful practice run earlier, but said he was distracted by the 6,000-strong crowd. "I came down waving to everyone, looking over Sydney Harbor, saw my dad, the kids and you, went to pull the brake and then boing," he explained to Winfrey. "Totally my bad."
"God he hit that hard," Winfrey told the audience later. "Ooooh, we're gonna see that on the news. Over and over and over again. 'Hugh injured today. Ziplining on Oprah.' "
Jackman later returned for a stunning finale, singing "I Still Call Australia Home" with the Qantas Children's Choir. He was joined by fellow guest Olivia Newton-John, then Keith Urban and Nicole Kidman and finally Russell Crowe as the crowd unfurled a gigantic Australian flag over their heads.
Mishaps aside, Winfrey said she's loved her time in Australia. "No matter what we show you, it does not compare to actually being here," she told her TV viewers. "I will be back."