Fallon, a former "Saturday Night Live" cast member, is expected to begin his new gig when outgoing host Conan O'Brien leaves to replace Jay Leno on "The Tonight Show" in 2009.

The announcement was made Monday by Marc Graboff and Ben Silverman, co-chairmen of NBC Entertainment and Universal Media Studios, at a press conference in New York.

"We couldn't be happier to have Jimmy back on NBC and to have our No. 1-rated late night team fully in place for the future," said Silverman. "Jimmy is more than just a likable guy and a great comedian, he is genuinely interested in what people have to say."

"Jimmy's proven track record and personality make him a natural for this important role that will bring a new generation of fans to 'Late Night,'" added Graboff. "He will put his own distinct mark on late night humor just as he did on 'SNL' and in his other creative endeavors."

NBC said the premiere date for "Late Night with Jimmy Fallon" will be announced at a later date.