[citation needed] Cousens was appointed a Member of the Order of Australia in the Queens Birthday Honours in June 2019 for services to the performing arts and the community.

In the 1980s he guest starred in a number of major Australian television productions, including The Timeless Land, Earth Watch, The Sullivans, The Young Doctors, Sons and Daughters and The Restless Years.

Major roles include The Phantom in London's West End production of The Phantom of the Opera; he also portrayed Marius in Les Misérables, Alex in Aspects of Love, Tony in West Side Story, Bobby in Company, Nanki Poo in The Mikado, Anthony Hope in Sweeney Todd: The Demon Barber of Fleet Street, and Chris in Miss Saigon in the Australian productions.

Cousens has been featured on a number of cast albums, including as Chris on the International Symphonic Recording of Miss Saigon, and as Charles Makin on the original cast album for Australian musical The Hatpin.

In 2012–13, Cousens produced and directed Freedom, starring Cuba Gooding Jr, William Sadler and Sharon Leal.