Cardi B to Co-Host ‘The Tonight Show’ With Jimmy Fallon on Monday

When they zig, he zags.

Cardi B will be co-host “The Tonight Show” with Jimmy Fallon next Monday night, the first time the show has ever had two people sharing hosting duties, NBC said on Tuesday.

Next Monday’s show will, as usual, stand out compared to his competitors: Mr. Fallon has kept his show joke-and-celebrity heavy while CBS’s Stephen Colbert and ABC’s Jimmy Kimmel have gotten increasingly political. In that time, Mr. Fallon’s ratings have declined while Mr. Colbert and Mr. Kimmel have seen their total viewerships go up.

Enter Cardi B.

The Bronx-born rapper appeared on Mr. Fallon’s show in December, and her segment on the couch became a viral hit. To date, the five-minute interview has collected more than 16 million views. She also appeared on the show in September when she performed “No Limit” with G-Eazy.

NBC said on Tuesday that Cardi B would join Mr. Fallon on “The Tonight Show” stage throughout the program, and would help interview that evening’s scheduled guests. She will also perform a song on the show. Her first album, “Invasion of Privacy,” debuts on Friday.

For the season, Mr. Fallon is averaging 2.8 million viewers, a 15 percent decline versus last year. Among adults under 50, Mr. Fallon remains the leader, but his ratings in that demographic have dropped 18.8 percent. Meanwhile, his CBS competitor, Mr. Colbert, is now averaging more than a million viewers better than “The Tonight Show,” an unimaginable turnaround from just two years ago. Mr. Colbert’s ratings have gone up 24 percent. Mr. Kimmel at ABC is now averaging 2.3 million viewers, and has seen his viewership figures tick up 2 percent.