He is known for his roles in the films Project X (2012), As Cool as I Am (2013), Hansel & Gretel: Witch Hunters (2013), Me and Earl and the Dying Girl (2015), Kong: Skull Island (2017), and Halloween Kills (2021).

[4] Mann attended Plano East Senior High School briefly before moving to California at the age of 17 to pursue acting.

[5] In 2009, Mann made his acting debut on the Nickelodeon sitcom television series iCarly portraying the role of Jeffrey.

[12] The same year, Mann appeared in the film Fun Size alongside Victoria Justice portraying the role of Roosevelt.

[21] In 2016, he starred as Matt in Some Freaks, a teen romance, Blood Father, opposite William H. Macy and Mel Gibson,[20][22] and the drama Brain on Fire, alongside Chloë Grace Moretz and Jenny Slate.

[23] In 2017, Mann played Reg Slivko in the fantasy action film Kong: Skull Island, and appeared alongside Bella Thorne in Amityville: The Awakening.

In 2019, Mann played Ted Hinton in John Lee Hancock's drama film The Highwaymen, which was released on Netflix in March of the same year.