The Republican candidates' prime-time debate on Fox News Channel drew 24 million viewers, a record audience for a presidential primary debate, according to Nielsen data provided by Fox on Friday.
The tally for Thursday's event was the highest non-sports telecast in cable history, a Fox spokeswoman said.
The brash style of billionaire real estate mogul Donald Trump, who has dominated news coverage in recent weeks, and the large pool of candidates participating in the debate - 10 - had spiked interest.
An earlier debate Thursday on Fox News Channel featured the other seven Republican candidates, whose low polling numbers kept them out of the prime-time debate.
The two-hour prime-time telecast on Fox News Channel, which is owned by 21st Century Fox, drew 7.9 million viewers aged 25 to 54, the key group for advertisers on cable news broadcasts.