Jason Reilly was born in Toronto, Canada, where he was trained at the National Ballet School Toronto. During his time as student he already danced in ballets such as The Nutcracker and Pastorale (both: James Kudelka), choreographers such as Glen Gilmour (in Boys Dance), John Neumeier (in Yondering) and David Nixon (in Sudden Impulse) created roles on him.

After his graduation in 1997 he joined the Stuttgart Ballet. In 2000/2001 he was promoted to Demi-Soloist, one season later to Soloist. Since the season 2003/04 he has been dancing as Principal Dancer.

With the Stuttgart Ballet Jason Reilly has danced numerous major roles in full-length ballets by renowned choreographers.

Jason Reilly has joined the Stuttgart Ballet on tours and guest performances all around the world. When the Stuttgart Ballet went on it’s tour to the USA in 2003 he gained international acknowledgement for the male title role in John Cranko’s Romeo and Juliet. Furthermore he has danced with internationally renowned female dancers like Alessandra Ferri, Evelyn Hart and Greta Hodgkinson. In the new production of A Streetcar named Desire (John Neumeier) in 2004 he danced the role of Stanley Kowalsky together with Alessandra Ferri. When Canadian star ballerina Evelyn Hart retired from her 30-year-long career and wished to dance the part of Juliet for one last time in April 2004, she asked Jason Reilly to be her Romeo. She also chose him as her dancing partner when she bid farewell to the stage in 2006. In October of the same year, Jason Reilly gave several guest performances of Glen Tetleys Voluntaries with the Royal Ballet in London. In 2007, he danced the role of Petrucchio in John Cranko’s The Taming of the Shrew with the National Ballet of Canada starring Greta Hodgkinson as Kate.

Due to his outstanding interpretation of classical roles in combination with his expression and technical brilliance in modern ballets Jason Reilly was named in the category “Outstanding Dancer” in the annual critics’ choice of the magazine ballettanz several times. In February 2006 Jason Reilly received the German Dance Award “Future”, which is awarded each year by the German Association for Dance Education and the German Association for the Promotion of the Art of Dance. In August 2023 he has been named "Dancer of the Year" in the critics' poll for the 2022/2023 season by the renowned magazine Tanz.

In September 2015 he was awarded the national title of "Kammertänzer".