Nearly 7 million viewers watched
According to Nielsen, the former Comedy Central star averaged 6.6 million on Tuesday as he stepped onto the Ed Sullivan Theater stage to succeed David Letterman on the late night program.
Among viewers in the 18 to 49 age group most sought after by advertisers, Colbert scored a 1.4 rating.
Colbert topped the usual late night leader "The Tonight Show Starring Jimmy Fallon," which averaged 2.9 million viewers and a .9 rating among 18- to 49-year-olds. ABC's "Jimmy Kimmel Live" averaged 1.7 million viewers and a .4 among 18- to 49-year-olds.
The ratings for Colbert's opening did not approach the audience levels for Fallon's premiere as "Tonight Show" host on Feb. 17, 2014, which drew a 11.3 million viewers and a 3.8 rating in the 18 to 49 demographic. However, that debut had the benefit of a massive lead-in from NBC's Olympics coverage in prime time.
Minneapolis was the highest rated market for Colbert's debut, scoring a 9.3 rating and a 27 share. In Los Angeles, the show had a 4.5 rating/15 share. Colbert captured a 5.7 rating/15 share in New York and a 7.1 rating/15 share in Chicago.
Colbert's premiere show included guests George Clooney and Republican presidential candidate Jeb Bush as well as an all-star musical performance led by Mavis Staples.
Fallon also made two cameo appearances in taped comedy segments.