More than 70 jobs are expected to be eliminated during the next few months due to the closings, Variety.com said Friday.
Some employees will stay onboard to handle the divisions' last handful of releases before the doors to Picturehouse and Warner Independent close in the fall.
Picturehouse still has "Mongol," "Kit Kittredge: An American Girl" and "The Women" to get out, while WIP is due to release "Towelhead" and "Slumdog Millionaire."
"With New Line now a key part of Warner Bros., we're able to handle films across the entire spectrum of genres and budgets without overlapping production, marketing and distribution infrastructures," Alan Horn, Warner's president and chief operating officer, told the trade paper. "After much painstaking analysis, this was a difficult decision to make, but it reflects the reality of a changing marketplace and our need to prudently run our businesses with increased efficiencies."
WIP was behind the films "Good Night, and Good Luck" and "March of the Penguins," while Picturehouse saw success with "La Vie en rose," "Pan's Labyrinth" and "A Prairie Home Companion."