Letterman used most of his monologue for jokes at his own expense. In revealing last week that he was the victim of an alleged blackmail scheme, Letterman also admitted to having sexual relationships with women who worked on his "Late Show."
When the laughs quieted down, Letterman apologized to his staff for "putting up with something stupid I've gotten myself involved in." Many had been humiliated by questions from reporters. Letterman said the relationships were in the past. He married longtime flame Regina Lasko in March, and said he is intent upon repairing their marriage.
"Let me tell you folks, I got my work cut out for me," he said.
CBS News producer Robert J. "Joe" Halderman has pleaded not guilty to charges of trying to extort $2 million from Letterman.
Although Letterman has acknowledged having more than one sexual relationship with staff members, Halderman referred to only one woman by name - Stephanie Birkitt - in his alleged extortion attempt, according to a law enforcement official who spoke on condition of anonymity because of the continuing investigation. Birkitt, Letterman's assistant, is Halderman's former live-in girlfriend.
The 5.7 million viewers who tuned in to Letterman Monday more than doubled the audience for NBC's "Tonight" show with Conan O'Brien, according to the Nielsen Co. It was slightly less than the 5.9 million who watched Thursday when Letterman broke the news of the alleged extortion attempt.
The ratings are a testament to the power of the Internet after Letterman's representatives released details of the scandal to the media about three hours before his show aired Thursday. His audience that night was more than a million more than usual, meaning word spread quickly and encouraged people to tune in.
The timing also couldn't be better for CBS, which has seen Letterman eclipse the "Tonight" show shortly after O'Brien took over. The "Late Show" is solidifying the lead partly because of the scandal and guests like President Barack Obama, who brought 7.2 million viewers when he appeared on Sept. 21.
Also appreciating the timing was the pistachio nut industry, which started its first-ever television advertising campaign Monday with commercials on Letterman and the highly anticipated NFL game between the Minnesota Vikings and Green Bay Packers.
"This is gravy for us," said Dominic Engels, vice president for marketing at pistachio maker Paramount Farms.
No advertisers have publicly asked to back out of the "Late Show" since the story broke, and analysts say they don't expect the incident to make a bottom-line difference to the CBS Corp.
"The ratings popped the first night," said David Joyce, analyst for Miller Tabek. "It appears as if it's going to be a non-story."
Letterman even got an endorsement from Martha Stewart, who said his actions aren't at all disturbing unless there was force involved.
"He's a very attractive man," she said. "Very appealing. Great sense of humor, obviously, and I think all this was done while he was still not married. Although it's still probably harmful to his wife ... But, you know, men are men. I've put up with it all."
Letterman's effort to be pro-active with the issue in a self-deprecating way is helping him control the story and his image, said Michael Gordon, head of a New York-based crisis public relations firm.
"What he can't control is if there are more revelations," he said. "If just one woman claims harassment, then his ratings will go down along with his career."
Letterman arrived on stage Monday to applause and cheers from his studio audience. After drinking it in, he grinned sheepishly and inquired, with a mock stammer, "Did your, did your weekend just fly by?"
After pausing for the audience's sympathetic laughter, he went on: "I mean, I'll be honest with you folks - right now, I would give anything to be hiking on the Appalachian Trail."
"I got into the car this morning," he added, "and the navigation lady wasn't speaking to me. Ouch."
His performance drew mixed reviews.
Entertainment Weekly's Ken Tucker called it "was such a superb hour of television ... that it reminded us all over again how invaluable he is."
"It is time for those calling for his head to calm down and let the man do his job, the job he does as no one else does, and no one will ever do as well again," Tucker wrote
But editorial page columnist Yael T. Abouhalkah of the Kansas City Star said Letterman's effort to poke fun at a serious situation "made the apologies he issued look rather lame."
Joel Keller of the Web site TV Squad advised Letterman to "stop talking about this mess, immediately."
"The more jokes he made, the more I felt that he was digging a hole he couldn't get out of," Keller wrote. "And then when he made that apology, sincere as it was, it felt like the hole just got much, much deeper."
Only one other late-night host, Craig Ferguson, made any reference to Letterman. Leno, Jimmy Fallon and NBC's "Saturday Night Live" had all made jokes in earlier shows, but everyone but Ferguson avoided the topic on their Monday night and Tuesday morning shows.
As host of the "Late Late Show," Ferguson follows Letterman's "Late Show." Letterman also is his boss, since Letterman's production company, Worldwide Pants Inc., produces the "Late Late Show."
"The person you work for, the person you admire and respect, is caught in an embarrassing situation," said Ferguson. "And your job is to be funny about that, whilst trying to keep your own job."
"So this is my last show," he joked.
Associated Press writer Colleen Long, Entertainment Writers Jake Coyle and Alicia Rancilio, Television Writer Frazier Moore and Business Writers Emily Fredix and Deborah Yao contributed to this report.