The cable network HBO drew the largest audience in its 30-year history for Sunday night's première of the latest series.
And for the first time, the cable network drew a larger American audience than any of the broadcast networks at the same time - an estimated 13.4 million viewers.
The Sopranos' audience from 9 to 10 pm on Sunday surpassed the top terrestrial broadcast show for the slot, NBC's Law & Order: Criminal Intent as well as CBS's venerable news magazine 60 Minutes.
The audience for The Sopranos was achieved in spite of the fact HBO reaches only one-third of the estimated 107 million American homes with TV sets.
"This is higher than I thought we had the potential to reach," said HBO's executive vice president David Baldwin.
The previous record-holder for most-watched broadcast on HBO was the 1989 championship boxing match between Mike Tyson and Frank Bruno, an HBO spokeswoman said.
The critically-acclaimed series, which stars James Gandolfini as a family-man mafia boss, was returning to HBO after a 16-month break.
The drama picked up where it left off, with Gandolfini's character Tony Soprano undergoing therapy in response to marital problems and money troubles in the family business.