Monday was Fallon's first show back after the injury, which led to him having emergency microsurgery and staying in intensive care for 10 days. Fallon told the audience that he tripped and fell in his kitchen and caught his finger on a countertop as he fell, turning it "sideways."
"Apparently the odds aren't great with these things," Fallon said. "Usually they're just going to cut your finger off."
But after a six-hour operation, doctors were able to save Fallon's finger - though he won't get feeling back in it for another eight weeks.
"I started losing it halfway through," Fallon said of his 10-day ICU stint. "I started reading books about the meaning of life. ... The meaning of my life is, I should be on TV. ... This is my job. I'm here to make you laugh. I'm here to make you have a good time."
Fallon went on to thank his friends and fans for support. Watch his full message below: