The action man leapt out of a helicopter above the Grand Canyon in Arizona - and fans got to watch the whole thing via a livestream on Will's YouTube page.
The leap was organised after the creators of the YouTube channel Yes Theory challenged Smith to bungee jump from a helicopter. He accepted on the condition that the stunt would benefit anti-poverty charity Global Citizen - and it would take place over the Grand Canyon.
Speaking to Ribeiro just before his big jump, Smith said, "Here's what happens in life - I say a lot of things I don't mean. So they (Yes Theory bosses) challenged me to bungee jumping and I was like, 'Ain't nobody challenge me to heli jumping. Oh, how about heli bungee over the Grand Canyon?'
"As I approached the canyon, there are things that I'm realising I probably should've thought about before."
His son Jaden added, "I can't believe he's doing this. It's crazy."
Will isn't new to bungee jumping from a great height - he took the plunge over Victoria Falls in Zimbabwe, Africa last year (17) and documented the leap of faith on his YouTube channel.
After the stunt, an exhilarated Will told Alfonso, "Nothing will ever be more scarier (sic) than that."
The actor turned 50 on Tuesday.