The 40-year-old star will reprise her role as Veronica Corningstone in the film starring Will Ferrell as Ron Burgundy, reported E! online.
"Christina will be back," Apatow said.
The producer said that the new film will also feature a number of celebrity cameos after attracting Jack Black, Ben Stiller and Luke Wilson for the original.
"I know that they want to do a lot of that. I just don't know who they're specifically thinking about," Apatow added.