Tanis was born and raised in Peace River, Alberta, Canada. She is a member of the Métis Nation of Alberta and is of Cree and Sioux descent. As a life-long athlete, Tanis was never a stranger to performance. She was a competitive figure skater for 15 years and was also cast in a local production of The Sound of Music at a young age.
 
Tanis attained her Bachelor of Physical Education degree at the University of Alberta in 2000. It was during this time Tanis took Drama 101 and fell head over heels in love with acting. She quickly got an agent and began booking roles in commercials and independent film.
 
In 2003 Tanis moved to Vancouver, BC to further pursue her career.  With a principal role on The Twilight Zone with Jeremy Sisto and Alicia Witt, playing Corb Lund's girlfriend in Hank William's First Nation and a string of roles in independent film under her belt, Tanis's career was continuing to develop. In 2008 Tanis decided to tackle New York City and immerse herself in serious training. She completed her Master of Fine Arts degree in Acting in 2011 and has been working steadily ever since.

Post-graduation, Tanis quickly became a highly sought-after Native actress in New York City. Stage career highlights include starring in Manahatta at the prestigious Public Theater, originating the lead role JANE/LE-LE WA 'YOU opposite Kimberly Guerrero and Brandon Oakes; originating the lead role of BONNIE RED BIRD in Powwow Highway, the first play adaptation of the novel; working with the famed Sheila Tousey (Thunderheart) at the William Inge Center for the Arts playing the lead role JOURNEY in What Would Crazy Horse Do?, and starring in countless other Off Broadway shows.

On screen, Tanis is best known for playing the groundbreaking role of LACY COUSINS, the Ocheole Tribal Chairwoman on Designated Survivor opposite Kiefer Sutherland. Tanis also plays the pivotal role of TAMMY, the Native American waitress, in the Emmy and Golden Globe winning Netflix original series House of Cards opposite Michael Kelly and Gil Birmingham, along with Kevin Spacey and Robin Wright.

​She is also delving into producing and writing and her inaugural film A Big Black Space won Best Canadian Short at Dreamspeakers International Indigenous Film Festival, won the Royal Reel Award at the Canada International Film Festival, was nominated for Best Live Action Short at the 12th Red Nation Film Festival, has garnered a broadcasting deal on ARTÉ in Germany, France and Belgium and is screening at events in colleges and universities all over North America.

Tanis's other love is strength training and fitness and has discovered she was born to deadlift. She also plans on becoming certified as a personal trainer in the future. Tanis is proud to say she has graduated with both Wayne Gretzky ('00) and Tony Kushner ('11) who each received honorary degrees the same years she completed hers.

Tanis lives out her passion for performing with tremendous support from her family and friends, and with a duty to Louis Riel, who is quoted as saying,

My people will sleep for one hundred years, but when they awake, it will be the artists who give them their spirit back.