Pelley, who has been at CBS since 1989, was named Tuesday to replace Katie Couric and will start in his new role June 6.
He said he instantly agreed when asked to fill the anchor seat that had been occupied by Walter Cronkite, Dan Rather and Bob Schieffer before Couric took over five years ago this fall. CBS has rarely been out of last place in the ratings over the past decade.
"The opportunity to lead the organization as managing editor of the evening news is something you aspire to, something you never believe you could actually achieve," Pelley said in an interview Tuesday.
CBS hasn't set an exit date for Couric, who is expected to start a daytime talk show at either ABC or CBS. Her contract expires June 4.
Pelley, 53, has been at "60 Minutes" since 2004, and he's won 14 Emmys and two Peabody awards. He joked that he had expected to stay at the job "all the way up to the mandatory retirement age of 95."
Jeff Fager, the CBS News chairman and executive producer of "60 Minutes," said he thought it was important for CBS to choose a new anchor from within. Even as it has fallen on hard times, CBS News is filled with veterans who take the network's tradition dating back to Edward R. Murrow very seriously, and many of them never quite took to Couric.
"There's a great tradition here and I think Scott's a terrific symbol of that tradition," Fager said. He called Pelley "as good a reporter as has ever worked at this network."
Fager also said he expects to name a replacement for "CBS Evening News" executive producer Rick Kaplan soon.
Pelley said "60 Minutes" gets many letters from viewers who say that they've been following an issue for a while but never truly understood what was going on until the newsmagazine did a story on it. He hopes viewers have the same attitude about evening news stories. Pelley will continue to do work for "60 Minutes," which has landed an interview with President Barack Obama to air this weekend.
"60 Minutes" airs on the same network, but its offices are across Manhattan's West 57th Street from the rest of the news division. The distance often seems greater than the ribbon of blacktop; Rather and Couric appeared on the program but weren't truly accepted there.
With Pelley and Fager - who produced the evening news during its last sustained period out of last place in the ratings, during the late 1990s - CBS is pushing for more cooperation from its broadcasts. If "60 Minutes" has a good story, CBS' new bosses want the evening news to highlight and try to advance it.
Pelley said he wants an evening newscast known for original reporting, unique insight into the news, great storytelling and fairness to all involved. He said he's not passing judgment on how it's done now, since he watches only sporadically due to his travel schedule.
Pelley "is a great reporter and a real gentleman, who cares deeply about the news," Couric said. "I know he'll put his own unique imprimatur on the broadcast and will do a great job carrying on the tradition of the 'CBS Evening News."'
The new anchor said he takes seriously his role as a leader and will push to make sure "there is CBS News DNA in every story."
"The anchor piece is the least important thing I do every day," he said. "It's the most visible, but it's the least important thing. The managing editor job is the most important at the end of the day."
Like Rather and Schieffer, Pelley is a Texan. The San Antonio native began his career as a 15-year-old copyboy at the Lubbock Avalanche-Journal and worked as a local news reporter in Lubbock and Dallas before catching on with CBS.
Evening newscasts have steadily dwindled in importance over the past few generations, but on a typical evening more than 20 million people watch news summaries at ABC, CBS or NBC, far more than anything on cable news. Pelley has a challenge in front of him: The pecking order of NBC's "Nightly News" with Brian Williams in first and ABC's "World News," for the past year with Diane Sawyer, in second, rarely changes.
"The last thing Scott needs from me is advice," Williams said Tuesday. "Or packing instructions. He's a fellow road warrior and a first-rate journalist, and he's filling a great chair. All I can offer is a hearty welcome to a highly competitive time slot, along with my congratulations."
If Pelley has a weakness in critics' eyes, it is that some see him as stiff and formal - the same things people said of Williams when he first started in 2004. Williams is now the subject of a New York magazine article on his comic stylings, and on Monday made a comfortable appearance on David Letterman's "Late Show."
"I don't do comedy," Pelley said, "although I appreciate Brian's comedy very much."
He said he hoped viewers who don't know him well will understand him as much like themselves, as a person who came from a small town and modest circumstances. "I have lived the American dream that we all aspire to," he said.