Kirshner started her career in 1989 in "Loving the Alien", a second-season episode of
War of the Worlds, as both Jo, a young resistance fighter who is captured and duplicated by the enemy aliens, and her
doppelgänger. Kirshner made her film debut in 1993 at the age of 18 in
Denys Arcand's
Love and Human Remains. She convinced her father to sign a "nudity waiver" to play a
dominatrix. The following year, she starred as a conflicted
exotic dancer in
Atom Egoyan's
Exotica. In 1996, she appeared in
The Crow: City of Angels. She also played Kitty Scherbatsky in the
1997 version of Anna Karenina. Kirshner also appeared in the first three episodes of
24 as the
assassin Mandy in 2001. She would later reprise the role for the second season's finale and in the latter half of the show's fourth season. Also in 2001, Kirshner played Catherine Wyler, "The Cruelest Girl in School", in
Not Another Teen Movie. The character is primarily a spoof of
Kathryn Merteuil (played by
Sarah Michelle Gellar) in
Cruel Intentions, and was partially based on Mackenzie Siler (played by
Anna Paquin) from ''
She's All That''. In
Marilyn Manson's music video for "
Tainted Love", which was featured on the movie's soundtrack, she made a
cameo appearance as her character Catherine Wyler. In 2004, Kirshner was cast as writer
Jenny Schecter, a main character in the drama series
The L Word. She remained with the show through 2009, for all six seasons. In 2006, she starred in
Brian De Palma's
The Black Dahlia in which she plays the young aspiring actress
Elizabeth Short, whose mutilation and murder in 1947 remains unsolved. While the film itself was critically panned, many reviews singled out her performance for acclaim.
Stephanie Zacharek of
Salon.com, in a largely negative review, notes that the eponymous character was "played wonderfully by Mia Kirshner..." In 2010, she was cast as Isobel Flemming, a guest role on
The Vampire Diaries. On April 20, 2012, it was announced that Kirshner would join the new
Syfy series
Defiance. On October 9, 2013, it was mentioned on the
Showcase blog that Kirshner would be one of several guest stars in season four of the television series
Lost Girl. From 2017 to 2019, she played the recurring role of
Amanda Grayson, mother of
Spock and foster mother of series protagonist
Michael Burnham on
Star Trek: Discovery (a role originated by
Jane Wyatt on the original
Star Trek). She later reprised the role in an episode of
Star Trek: Strange New Worlds. On September 5, 2019,
Entertainment Tonight news outlet
ET Online reported that Kirshner would play a character in
Lifetime's film
The College Admissions Scandal with co-star
Penelope Ann Miller in roles inspired by real-life actresses
Lori Loughlin's and
Felicity Huffman's involvement in a massive college admissions bribery scam. Describing her role, Kirshner was quoted saying "This story is about privilege and corruption and it's about people who don't follow the rules because they think they're above rules... My character [based on Loughlin but named "Bethany" in the film] is so corrupt, greedy, narcissistic, self-centered, and the dialogue is hilarious, so I'm glad that they're able to capture humor about this as well." In September 2020, it was announced that Kirshner would co-star with
Ben Savage in a
Hallmark Channel holiday film entitled
Love, Lights, Hanukkah!, which premiered on December 12, 2020. Kirshner plays a restaurant owner named Christina, who learns of her
Jewish ancestry through a
DNA test. == Philanthropy ==