LOS ANGELES — With returning hosts Brad Paisley and Carrie Underwood and a much-talked-about performance by Taylor Swift, ABC’s CMA Awards roped in their biggest audience in four years.

The 47th annual CMAs drew an average of 16.6 million viewers Wednesday night, up 21 percent compared with last year’s telecast and the best performance in total viewers since 2009, according to early numbers from Nielsen.

In the advertiser-coveted young-adult demographic, the event drew a rating of 4.7, up 24 percent from last year, when the show aired on a Thursday. Compared with two years ago, the last time the show took place on a Wednesday, last night’s rating was down slightly in the 18-to-49-year-old segment.

George Strait won the top prize, entertainer of the year, while Swift won the pinnacle award, honoring her worldwide success. During her performance, Swift was accompanied by an all-star band of country vets including Vince Gill, Alison Krauss and Sam Bush.

With the big music night, ABC was easily the top-rated network of the night, followed by CBS, which drew 9.25 million viewers on average and a rating of 2.2. (In 18-to-49, a rating point equals roughly 1.3 million viewers.)