The television audience for the annual Grammy Awards show dipped to 18.7 million viewers, a 6% drop from 2019, ViacomCBS's broadcaster CBS said on Monday.
Last year, the highest honours in the music industry were watched by 19.9 American television viewers.
Sunday's 3-1/2 hour live show from Los Angeles saw teen sensation Billie Eilish sweep all four top awards - album, song record of the year and best new artist, becoming the first woman to do so.
Performers on the live telecast also paid tribute to basketball star Kobe Bryant, who was killed in a helicopter crash hours before the Grammy show took place in the venue that is home to his former team, the Los Angeles Lakers.
The least-watched Grammys was in 2006, when 17 million Americans tuned in. Sunday's data, compiled by Nielsen, does not include those who watched in bars or public places
Despite the drop, CBS noted that the Grammys had the largest audience, and social media engagement, for a prime time entertainment show so far this year, beating the 18.3 million who watched the Golden Globes on Jan. 5.