Conan O’Brien scored a sweeping win in the ratings on Friday night, continuing what looks increasingly like a victory lap in finishing his run on the “Tonight” show.

For the first time in several weeks, Mr. O’Brien was ahead of his main rival, David Letterman on CBS, even in the broad household ratings that are delivered the next day. Mr. O’Brien had a 3.2 household rating Friday night, to a 3.0 for Mr. Letterman.

And the margin of his win among the younger adult viewers preferred by advertisers grew even larger in preliminary numbers from the top 24 cities. In that measure, called the local people meters, Mr. O’Brien hit his biggest number of what has been a big week for him, a 1.9 to just a 0.8 for Mr. Letterman among viewers 18 to 49.

With a deal to settle his NBC contract expected to conclude as early as today, Mr. O’Brien, who is expected to have one more week as the “Tonight” host next week, has turned the attention surrounding his departure into a ratings bonanza.