Since its introduction to the United States, Game Show Network credited Who Wants to Be a Millionaire with not only single-handedly reviving the game show genre, but also breaking new ground for it. The series revolutionized the look and feel of game shows with its unique lighting system, dramatic music cues, and futuristic set. The show also became one of the highest-rated and most popular game shows in U.S. television history, and has been credited with paving the way for the rise of the primetime reality TV phenomenon to prominence throughout the 2000s.
The U.S. Millionaire also made catchphrases out of various lines used on the show. In particular, "Is that your final answer?", asked by Millionaire's hosts whenever a contestant's answer needs to be verified, was popularized by Philbin during his tenure as host, and was also included on TV Land's special "100 Greatest TV Quotes and Catch Phrases", which aired in 2006. Meanwhile, during his tenure as host, Cedric signed off shows with a catchphrase of his own, "Watch yo' wallet!"
The original primetime version of the U.S. Millionaire won two Daytime Emmy Awards for Outstanding Game/Audience Participation Show in 2000 and 2001. Philbin was honored with a Daytime Emmy in the category of Outstanding Game Show Host in 2001, while Vieira received one in 2005, and another in 2009. TV Guide ranked the U.S. Millionaire #7 on its 2001 list of the 50 Greatest Game Shows of All Time, and later ranked it #6 on its 2013 "60 Greatest Game Shows" list. Game Show Network ranked Millionaire #5 on its August 2006 list of the 50 Greatest Game Shows of All Time, and later honored the show in January 2007 on its only Gameshow Hall of Fame special.