LOS ANGELES — Sheila Nevins, the grande dame of documentary film, who left HBO in 2017 after nearly 40 years, has joined MTV to start a nonfiction film and specials division.

Ms. Nevins, 80, helped change the image of documentaries from stodgy to provocative during her reign at HBO, delivering the Oscar-winning “Citizenfour,” the ribald “Taxicab Confessions” and the incendiary “Going Clear: Scientology and the Prison of Belief” — along with roughly 1,500 other films and series. At MTV, a division of Viacom, she will develop projects for the network and for outside buyers, including streaming services.

“We couldn’t believe that Sheila would even take a meeting with us,” Chris McCarthy, the 44-year-old president of MTV, said in interview on Tuesday. “As we grow and expand MTV, we see our role as amplifying young people’s voices. We’re excited for her to bring a new generation of filmmakers to the forefront.”

Ms. Nevins, true to form, gave a blunt answer when asked by phone why she was interested in the job.

“Somebody wants me!” she said. “Chris, who is my new boyfriend, did not want to put me out to pasture.”