Monique Allen trained with the Manly Warringah Gym Club before joining the Australian Institute of Sport (AIS). At the Commonwealth Games in Auckland in 1990, she was awarded 9.875 points for her routine on the uneven bars and became the first Australian female gymnast to receive a gold medal.
Allen competed in the World Championships in 1987, 1989 and 1991. In 1989, she came 25th in the all-around competition at this event, becoming the first Australian to make the second round. That same year, she qualified for the World Cup Circuit and was named Sportstar of the Year for the AIS. Allen competed at the Olympic Games in Los Angeles (1984), Seoul (1998), and Barcelona (1992), and appears on the AIS Roll of Honour for each of those years. Placed 19th at Barcelona, she was the highest ranking Australian at an Olympic Games.
Monique Allen retired from competition after the Olympic Games in Barcelona. She and her husband Wayne have a daughter, Ruby.