As Variety reported, approximately 39.87 million Americans watched Biden's inauguration, compared with 38.35 million viewers for Trump's.
Around 9.9 million people tuned into CNN's broadcast, while 7.66 million watched the event on ABC News and 6.89 million watched it on NBC. MSNBC attracted 6.5 million viewers, CBS 6.07 million and 2.74 million followed the inauguration on Fox News.
CNN's audience rose from 3.3 million in 2017, a jump of 196 percent. The conservative-leaning Fox News' numbers, meanwhile, fell by 77 percent from 2017.
Across the six major cable networks, the 39.87 million figure represented an increase of four percent over the 2017 event.
The figures cited in the report refer to the half-hour swearing-in ceremony.
The event -- which featured numerous celebrities and entertainers, such as Lady Gaga and Jennifer Lopez -- attracted 29.45 million viewers between the hours of 11 a.m. and 4 p.m. across the six networks.
As The Hill noted, the surge in ratings may be a result of the coronavirus pandemic. While millions of Americans watch the historic affair at home every four years, nobody was able to attend this edition in-person due to measures that were introduced to reduce the spread of the deadly disease.
A televised special titled Celebrating America followed the inaugural parade. It featured artists such as John Legend, Kerry Washington, Tom Hanks and Bruce Springsteen.Trump, who often pointed to his TV ratings as evidence that he is doing a good job as commander-in-chief, has yet to comment on Nielsen's data.
Trump's apparent obsession with ratings began in 2004, when his reality show The Apprentice premiered, per a report from Vanity Fair.
According to early Apprentice publicity manager Jim Dowd, the real estate mogul "knew nothing about Nielsen ratings" at first, but "within a week, he started to really study up."
"When he studies up on something that involves numbers and entertainment, then he's going to really kind of let that sink in. And we'd have calls every single day after [a show aired], he'd usually start calling at eight in the morning, but the ratings don't come in until 10. I'd always have to tell him, 'Mr. Trump, we have to wait until 10. As soon as they come in, I will call you.'"Last year, as the number of COVID-19 cases surged across the nation, Trump touted television ratings of his daily press conference. In a series of tweets, he described the briefings as a "hit," comparing them to The Bachelor.