James Corden poses for pictures on the red carpet during the 2015 Critics' Choice Awards. Kevork Djansezian

Just two weeks into James Corden's tenure on "The Late Late Show," CBS is crowing about the new host. Despite being virtually unknown when he was tapped to succeed Craig Ferguson this past fall, the 36-year-old Corden has earned strong ratings and driven huge digital growth, instantly making a show that had been a digital afterthought competitive with other late-late hosts like Seth Meyers.

Ever since his first episode aired on March 23, Corden has exceeded expectations. His big debut attracted 1.66 million viewers,according to Nielsen, the largest audience “The Late Late Show” had drawn in five years, and thanks to a tour de force segment with Tom Hanks, it was also one of the most-discussed shows on social media, rubbing elbows with social media giants like "WWE’s Monday Night Raw." He is also holding on to most of the audience David Letterman is leaving him when the “Late Show” host signs off.

But perhaps most encouraging for CBS is the growth Corden has driven on social media, an increasingly vital arena for late-night television. After nearly a decade of lackluster growth for "The Late Late Show" on YouTube, Corden has increased the show’s subscriber base by more than 300 percent, to more than 141,000. That surge was enough to put him in the same ZIP code as NBC’s Seth Meyers (195,000 subscribers), though it’s still quite far off late-night heavyweights like Jimmy Fallon, Jimmy Kimmel and Conan O'Brien, who all have millions of subscribers. According to CBS, Corden has also pushed “triple-digit” growth in unique visitors on CBS.com. While CBS still makes most of its money from broadcast advertising, it does monetize its late-night clips on YouTube.

Though he’s been on the air less than a month, it appears Corden wants his “Late Late Show” to be marked by spontaneity and unpredictability. Corden and his showrunner, Ben Winston, who were the youngest host/show-runner tandem until Trevor Noah was named Jon Stewart’s successor on Monday, are both new to American late-night television, and both men built their careers producing content for audiences much younger than the 50-plus demographic that forms the bedrock of network late-night TV programming. Winston worked on Simon Cowell’s hit music reality show “The X Factor” and helped produce special programs for the British boy band sensation One Direction, while Corden rose to stardom in Britain via the sitcoms "Fat Friends" and “Gavin & Stacey.” The one-man show he wrote, "One Man, Two Guvnors," earned him a Tony Award when it came to the United States after a successful run in the U.K.

Keeping this momentum going without high-powered guests will be a key challenge for Corden. Publicists are not always excited about the late-late time slot, and Winston has said many have been less than enthusiastic about the way that all of the night’s guests come out at the same time. But as long as Corden can keep the energy and suspense on high, he should have no problems; the show's 18-49 viewership leapt 33 percent by the end of its first week.