Guy Montgomery was born on 29 September 1988 in Wellington, New Zealand, to Charlotte Vanessa Jane Hallifax and Stephen Christopher Montgomery. He spent part of his childhood in Sydney, Australia, before the family settled in Christchurch, where he grew up with an older and younger sister.

Montgomery studied at Victoria University of Wellington, earning a Bachelor of Arts in theatre, film, and media. During this period he developed an interest in performance and comedy, eventually deciding to pursue stand-up professionally rather than careers in teaching or advertising.

He began performing comedy internationally around 2010, spending time in Montreal and Toronto to gain stage experience. After returning to New Zealand, he established himself in the comedy scene and later moved to New York while building a career in stand-up and podcasting.

Montgomery became widely known for creating and hosting the panel game show Guy Montgomery’s Guy Mont‑Spelling Bee, which began as an online comedy game during the COVID-19 lockdown and later became a television series. The show airs in New Zealand, Australia and BBC Three, where Montgomery serves as the host and creator.