Tanis was born and raised in Peace River, Alberta. She is a member of the Métis Nation of Alberta from Region VI and is of Plains Cree descent. Her family comes from the Red River Métis. Her great, great Grandmother, Marie Rose Cardinal, was a member of the James Seenum Band and took scrip during the signing of Treaty 6.

Tanis is best known for playing JANE HALFTOWN, Cayuga Tribal Council Leader, on Billions opposite Paul Giamatti; SARAH WATERS, a Mohawk mother on FBI: Most Wanted opposite Julian McMahon, LACY COUSINS, Ocheole Tribal Chairwoman on Designated Survivor opposite Kiefer Sutherland; and TAMMY, the Native American waitress  on House of Cards opposite Michael Kelly. On stage she has originated multiple leading roles including JANE/LE-LE-WA'YOU in Manahatta at The Public Theater and Oregon Shakespeare Festival, CONNIE FARMER in Smoke at Signature Theater and ROBERTA LAFORME in Glenburn 12 WP at 59E59 Theaters. She does voiceover work and also narrates audiobooks for Penguin Random House, Audible, Hachette and Simon & Schuster. 

Her production company, TDEP Productions, focuses on uplifting contemporary Indigenous stories and smashing harmful Indigenous stereotypes. Her debut short 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, garnered a broadcasting deal on ARTÉ in Germany, France and Belgium and has screened at events in colleges and universities all over North America. She is now developing multiple Indigenous-led series and features.

She has spoken on panels such as the Casting Society of America's Native American and Indigenous Actor Town Hall, SAG-AFTRA Foundation Native American Actor Panel and Decolonize Hollywood: SXSW via The New School. She sits on the SAG-AFTRA Native American Committee, is on the board at Peace Region Independent Media Arts Association, is the tribal liaison at AlterTheater and freelances as a casting consultant and assistant.

Tanis holds a Bachelor of Physical Education in Physical Activity and Sport Performance from the University of Alberta and a Master of Fine Arts in Acting from The New School for Drama and has a certificate in Personal Training. Tanis is proud to say she has graduated with both Wayne Gretzky (UofA) and Tony Kushner (NSD) 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."