Alexy graduated from the John Curtin College of the Arts in 2000, after doing specialist dance and theatre courses. Afterwards, she went to The Actors College in London, Le Centre des Arts Vivants and The Peter Goss Dance Studio in Paris, and earned a six-month theatre degree at the University of Colorado at Boulder (United States).
Alexy began her acting career at the age of ten, making her debut in television series Bush Patrol. The following year she appeared in her first leading television role, the children's series The Gift, for which she played the part for the complete first and only season. Her second leading role was in the series Parallax, another television series which was cancelled after just one season. She gained notability for her role as Tayler Geddes on Logie Award-winning television series McLeod's Daughters; she first appeared at the end of season 6, in which her character came to Drovers Run to get revenge on Regan McLeod, whom she held responsible for the death of her father.
Alexy's other television credits include Fast Tracks, All Saints, The Strip, Packed to the Rafters. In 2011, she began appearing on American television, in the series' Law & Order: Special Victims Unit and Blue Bloods. She starred in the Australian film West in 2007, playing a supporting role opposite Khan Chittenden and Nathan Phillips.
Alexy took part in a back door pilot for the proposed TV series NCIS:Red in early 2013, the cast of which appeared in the spin-off debut double-episodes of NCIS: Los Angeles "Red, Part 1" and "Red, Part 2" in March that year. The series was ultimately not picked up by the network.
|2005||The Umbrella Condition||Holly||Short|
|2017||People You May Know||Abigail|
|1996||Bush Patrol||Eloise||TV series|
|1997||The Gift||Sharon||Main role|
|1998||Fast Tracks||Alana Burroughs||TV series|
|2004||Parallax||Katherine Raddic||Main role|
|2005–06||All Saints||Nicole Higgins||Episodes: "Immortal", "No Way Out"|
|2006–2009||McLeod's Daughters||Tayler Jane Geddes||Guest role (season 6), main (season 7–8)|
|2008||The Strip||Cherry Cunningham||Episode: "1.6"|
|2008||Packed to the Rafters||Lauren Valco||Episode: "Taking the Lead"|
|2011||Law & Order: Special Victims Unit||Danielle 'Dani' Hynes||Episode: "Double Strands"|
|2011||Blue Bloods||Ellen Sloan||Episode: "Innocence"|
|2011||Unforgettable||Laura||Episode: "Lost Things"|
|2012||Nurse Jackie||Hip Replacement Patient||Episode: "Chaud & Froid"|
|2012||Damages||Gitta Novak||Recurring role (season 5)|
|2013||Castle||Candice Mayfield||Episode: "Death Gone Crazy"|
|2013||NCIS: Los Angeles||Claire Keats||Episodes: "Red: Parts 1 & 2"|
|2013–2015||The Americans||Annelise||Episodes: "The Clock", "Yousaf", "EST Men", "Baggage"|
|2014||The Crazy Ones||Megan||Episode: "The Lighthouse"|
|2014–15||Royal Pains||Charlotte||Episodes: "I Did Not See That Coming", "Oh, M.G.", "A Bigger Boat", "Ganging Up", "Rebound"|
|2015||NCIS: New Orleans||Savannah Kelly||Episodes: "My Brother's Keeper", "You'll Do", "How Much Pain Can You Take?"|
|2015||Aquarius||Martha Kendall||Episode: "Sick City"|
|2016–17||Outsiders||G'Winveer Farrell||Main role|
|2018||Dirty John||Maggie||Episode: "Remember It Was Me"|
|2020||The Blacklist||Victoria Fenberg||Episode: "Victoria Fenberg (No. 137)|
- Popcorn (1999)
- Return to the Forbidden Planet (2000)
- Mice (2001)
- Resident Alien (2002)
- Six Characters Looking for an Author (2003)
- Ghost Train (2004)
- The Chatroom (2004)
- Codes of Practice (2005)
- "Tayler Geddes (Gillian Alexy)". ninemsn.com.au. Archived from the original on 9 September 2011. Retrieved 8 November 2011.
- "West". screenaustralia.gov.au. Archived from the original on 5 April 2012. Retrieved 11 November 2011.
- "Jonathan Groff Cast In Michael Lannan HBO Pilot, Gillian Alexy Joins 'NCIS: LA' Spinoff". Deadline.com. 8 February 2013. Retrieved 8 February 2013.
- Andreeva, Nellie (5 November 2012). "CBS Prepping 'NCIS: LA' Spinoff Created By Shane Brennan As Planted Two-Part Episode". Deadline. Retrieved 6 November 2012.
- "'NCIS: Red' not going forward as series at CBS". digitalspy.co.uk. 15 May 2013. Retrieved 4 July 2013.
- Gillian Alexy at IMDb
- Gillian Alexy biography at Perth Theatre Company
- Gillian Alexy biography at TVSA (South Africa)