Smart is thus the only woman to have won an award for all seasons of a television series.
"What a journey it has been," Smart said from the stage.
This year's award for best actress in a comedy series is the 75-year-old's eighth Emmy, tying her for the record for most statuettes by an actor. Cloris Leachman and Julia Louis-Dreyfus also have eight.
The series "Widow's Bay" and "The Pitt" are predicted to be big winners at the gala.
