Although it was officially formed as 31/42 RQR in January 2008 by the amalgamation of two previously existing infantry battalions—the 31st Battalion, The Royal Queensland Regiment and the 42nd Battalion, The Royal Queensland Regiment— the unit has a long history, and can trace its lineage back to units formed in 1881 as part of the colonial defence forces of the state of Queensland.
These units were mainly used in home defence duties, although during the Second Boer War and World War I many of their members volunteered for overseas service and by virtue of this service battle honours from these wars were bestowed upon these units.
During World War II, both of these units were called upon to play an active role in the fighting in the Pacific, thus earning more battle honours for themselves.
After the war, these units were disbanded and then reformed as part of the Citizens Military Force in 1948, which was a forerunner to the current Australian Army Reserve, and as a part of that organisation both 31 and 42 RQR continued to exist in various forms for the next 60 years before it was decided to amalgamate the two units early in 2008.
Currently, 31/42 RQR has depots located along the Queensland coast from Gladstone to Cairns. In February 2009 the battalion returned from a successful deployment as part of Rifle Company Butterworth Rotation 84.
The motto of the Royal Queensland Regiment is 'Pro Aris Et Focis', which is Latin for ‘For Alters and Hearths’.