Schieffer praised his predecessor and told a gentle anecdote to reassure critics that he planned to tell the news with no agenda.
"Many of you have known and trusted me over the years," Schieffer said at the end of his first broadcast. "I take that as a high compliment and I promise you this: I'll never take that trust for granted."
It's not clear exactly how long Schieffer will be in the job; CBS has called him an interim anchor until network chief Leslie Moonves (search) figures out a next step for the third-rated evening news broadcast.
For one last night on Wednesday, Dan Rather was No. 1 in the ratings.
CBS was first in the preliminary Nielsen Media Research (search) ratings among the three network evening newscasts on Rather's last day as anchorman, followed by NBC and ABC. About eight million households tuned in to watch Rather, roughly two million more than his audience last week.
For several years, CBS has finished a distant third in the ratings. Back in the 1980s, Rather was the top-rated newscaster, before being eclipsed first by ABC's Peter Jennings and NBC's Tom Brokaw.
Schieffer opened his first broadcast by saying, "Tonight, we turn a page at CBS News." A few new wrinkles were on display, including an opening segment where individual correspondents introduced their stories.
At the end, Schieffer saluted Rather, who didn't mention Schieffer's name the night before.
"Dan will be remembered for the remarkable body of work he has compiled over four decades, but I'll remember him for his love of the news and the fierce determination and courage to go wherever the news was breaking," he said.
But Schieffer seemed to have in mind the critics who long accused Rather of being biased against Republicans when he told a story about the Washington Post's famed Watergate reporter, Bob Woodward (search). Woodward was asked recently about his mindset when he and Carl Bernstein (search) embarked on the story.
"Woodward said, 'We didn't have an agenda and we didn't know how it would end. We were just trying to find out what happened,'" Schieffer said.
"That's what we'll try to do — find out what happened and tell you about it in clear and concise language," he said. "If we do that — and do it well — you'll take it from there."
Schieffer, 68, is a veteran Washington hand who will continue as host of "Face the Nation" (search) on Sundays as he fills in for Rather. He will also likely anchor for CBS in the event a major news story warrants special reports.
Moonves has said he is likely to seek "revolutionary" changes in the evening news format, likely with multiple anchors.