Brenna started her acting career at age 9, performing in local theatre productions and school plays. Her first film role was in Scooby Doo 2: Monsters Unleashed at the age of 12 and from there she went on to secure supporting and guest star roles in shows such as Charlie St. Cloud, Life Unexpected, R.L Stine's The Haunting Hour: The Series, The Dead Zone, Stargate SG-1, Psych, Kyle XY, Masters of Horror, X-Men: The Last Stand, Beneath, Knights of Bloodsteel and the Troop, as well as a lead role in Zixx: Level Two, for which she was nominated for a Leo Award and Zixx: Level Three.
Aside from film and television, Brenna is an accomplished voice actor, having worked as a guest star as well as a lead in several anime shows such as Dragon Ball Z, Hamtaro, InuYasha, Elemental Gelade and many others. She has also worked on several motion capture productions for Rainmaker Entertainment including Barbie as Rapunzel, Barbie in Swan Lake and Tony Hawk's Boom Boom Sabotage. She was a lead role in Marvel's animated feature Next Avengers: Heroes of Tomorrow and, most recently, as a recurring role in Marvel's animated television series Iron Man: Armored Adventures.