In 2015, Borg co-starred in Pitch Perfect 2 as a leader of the German a cappella group Das Sound Machine (also known as DSM). This led to appearances on talk shows such as Last Call with Carson Daly, as well as the first of many appearances on the Comedy Central game show @midnight. Buddymoon, a feature film written and produced by Borg, David Giuntoli, and filmmaker Alex Simmons, and starring Borg and Giuntoli, was shown at several major film festivals in early 2016. It won the Audience Award for Best Narrative Feature at the Slamdance Film Festival and was acquired by Gravitas Ventures and Orion Pictures for theatrical release. Later in 2016, Lionsgate Films announced a development deal with Borg under which he will serve as star, executive producer, and writer of two upcoming feature films. Beginning in 2017, he has done a great deal of voice acting, appearing in roles such as Hans the Horse in Blue Sky Studios' Ferdinand and the personal assistant Maybe in Disney's Oscar-nominated feature Ralph Breaks the Internet. He also voices a part in Trolls World Tour, produced by DreamWorks Animation and released in 2020.
In addition to his film work, Borg has acted in a number of TV series, including Curb Your Enthusiasm, Workaholics, Silicon Valley, Counterpart, and The Good Place. In 2015, he co-hosted E!'s Live from the Red Carpet pre-show at the Billboard Music Awards. He has been a guest on the TBS talk show Conan several times, including an episode in which he served as Conan O'Brien's informal guide to Germany when the show traveled to Berlin for a week. In 2017, Borg's own social action special Flulanthropy premiered on the streaming channel Seeso. He has also done voice acting in several series, including Archer, The Mr. Peabody & Sherman Show, and Tangled: The Series. Borg voices a leading role as Mega Fat CEO Baby in the DreamWorks Animation/Netflix series The Boss Baby: Back in Business.
Also in 2015, Borg released a five-track EP titled I Want to Touch You. Videos for all of the tracks were posted to his YouTube channel. In early 2016, he released a full-length album called Animalbum, so named because all of the songs on the album are related to animals, both real and mythological. It was produced by comedian and producer of The Bachelor, Elan Gale. In 2019, Flula released a single titled 'Self Care Sunday', featuring the American comedic music group Ninja Sex Party, to Spotify.