Horn's first film acting credit was in 2006 for the
CBC television mini-series
Indian Summer: The Oka Crisis (for which she had been present at the real-life event sixteen years earlier). Horn landed a role in the 2007 drama film
The Colony, directed by Jeff Barnaby. In 2008, she appeared in the TV film
Moccasin Flats: Redemption and was nominated for a
Gemini Award for her role. She also appeared in
Journey to the Center of the Earth that year, also starring
Brendan Fraser. In 2009, Horn starred in
The Trotsky, directed by
Jacob Tierney, playing a Montreal high school student. In
Web of Lies, a TV movie about a cybersecurity specialist accused of fraud, she played a hacker named Spider. She appeared in
The Wild Hunt, directed by Alexandre Franchi and in Reginald Harkema's
Leslie, My Name Is Evil as a member of
Charles Manson's death cult. The three Canadian films were selected for the
Festival du Nouveau Cinéma.
The Trotsky and
The Wild Hunt made the Top 10 Canadian films list at the 2009
Toronto International Film Festival. Horn starred in the CBC television sitcom
18 to Life as Monica Bellow. The series was picked up by the
CW network and it aired in the US in August 2010. Horn filmed a second season in Montreal in mid-2010. Horn voiced several roles in
By the Rapids, an
APTN cartoon which she had made in collaboration with Joseph Tekaroniake Lazare. She also shot an APTN
television pilot,
Escape Hatch, with Mohawk writer-director
Tracey Deer. In 2010, Horn again worked with Jacob Tierney in the film
Good Neighbours. In 2011, Horn starred in the horror
anthology film The Theatre Bizarre, and played a priestess in
Immortals. She filmed
Penthouse North with
Michelle Monaghan and
Michael Keaton and shot a CBC comedy
pilot. Horn voiced the role of Kaniehtí:io, the Native American protagonist's (Ratohnhake:ton) Mohawk mother, in the 2012 video game ''
Assassin's Creed III, developed by Ubisoft. The same year, she wrote and directed her debut film, The Smoke Shack
, in association with the National Screen Institute. In 2013, Horn played Rynn, an Irathient spirit rider, on the Syfy TV series, Defiance, and played Dorothy from The Wizard of Oz in "Slumber Party", an episode of the CW series Supernatural. She also appeared in Embrace of the Vampire starring Sharon Hinnendael, a remake of the 1995 horror film of the same name, in the television special Gavin Crawford's Wild West and in the Amazon series The Man in the High Castle (TV Series)''. Horn appeared in a recurring role as Tanis in the CraveTV series
Letterkenny, for which she won the
Canadian Screen Award for
Best Supporting Actress in a Comedy Series at the
10th Canadian Screen Awards in 2022. Horn has also taken up the role of Consulting Producer on the
Letterkenny spinoff show
Shoresy, where she was tasked with ensuring the faithful portrayal of the show's many Indigenous characters. In 2020, Horn appeared as a panelist on
Canada Reads advocating for
Eden Robinson's novel
Son of a Trickster. From 2021–2023, she played a recurring role as
Deer Lady in the FX/Hulu show
Reservation Dogs. In 2022, Horn appeared in a recurring role as Feather Day in season 2 of the Peacock series
Rutherford Falls.
Seeds, her debut film as a director, premiered in the Discovery program at the
2024 Toronto International Film Festival, and was longlisted for the 2024
Jean-Marc Vallée DGC Discovery Award. ==Personal life==