“Rosie Live,” the one-hour special to be shown by NBC on Wednesday night, is an audition.

The Thanksgiving-eve audience will see an attempted revival of the variety show format, a staple of television in the 1960s and ’70s. Taking pages from Carol Burnett, Ed Sullivan and Sonny and Cher, the show will serve up Broadway dancers, celebrity appearances, musical acts and comedy sketches. Rosie O’Donnell, an executive producer and the host, sees a template for a weekly series.

“For about the past five years I’ve been pitching this exact show,” she said last week, taking a break from rehearsals at the Ripley-Grier Studios on Eighth Avenue, in Midtown Manhattan. “I’ve done it a million times in my head already.”

Ms. O’Donnell isn’t the only variety host in waiting. The broadcast networks are making expensive bets that the format is finally ready for an encore.

“The entire industry has been trying to figure out a way to bring back variety in some way,” Mike Darnell