Wallem will be overseeing the Christina Applegate sitcom's transition from the single-camera format to multi-camera, according to TV Guide.
Up All Night's previous showrunner Tucker Cawley is departing the series to become The Mindy Project's consulting producer.
NBC announced Up All Night's format change in late October, along with ordering five more episodes of the show's second season.
The show will be taking a three-month hiatus, before switching to the more traditional multi-camera sitcom style.
Bob Greenblatt, president of NBC, has said that the new production style will "infuse the show with more energy".
"We think we can make a seamless tradition to the new format. Also, we're committed to the multi-camera form and this will give us another show to consider for next season in this new format," Greenblatt said on October 29.
Up All Night airs Thursdays at 8/7c on NBC.