Speaking about his new title, the 46-year-old revealed that, after being "picked on" as a kid, it was a "nice surprise".
Perhaps it's because Idris Elba has always been considered one of the most handsome actors in the world, while last year's victor Blake Shelton is known more as that joking, good-old-boy country singer who spars with Adam Levine on "The Voice".
"It's an honor", he told Fallon via Skype. "My mum is going to be very, very proud".
So, how does the magazine pick its victor every year?
"I'm honoured & thankful", Elba wrote on Instagram after the announcement, before directing fans attention to tomorrow's elections. "They like the idea of a guy who would be a good husband and father". But to be honest, it was just a nice feeling.
Here are five ways Elba meets the criteria.
"I was very tall and skinny", recalled Elba, who stands at 6-foot-3.
The dad of two - of 16-year-old daughter, Isan and 4-year-old son, Winston - said he strives to live with as few regrets as possible.
"And my name was Idrissa Akuna Elba, OK?" he said.
'I've been ugly my whole life, ' Shelton, 43, said in a statement previous year.
He is only the third non-white man to be named by the magazine, along with Denzel Washington and Dwayne Johnson. We're just disappointed Shelton didn't fly out to London to hand him a "Sexiest Man Alive" crown or something.