The battalion was originally formed in 1973 by linking together both the 8th and 9th Battalions of the Royal Australian Regiment.
Over the next twenty-four years the battalion would remain on the Australian Order of Battle based at Enoggera Barracks in Brisbane, Queensland, until it was disbanded in 1997 amid a number of Defence-wide cutbacks introduced by the Howard government.
In 2006 it was announced that the battalion would be re-raised as part of a plan to expand the size of the Army and since then it has established itself as a fully deployable infantry battalion as part of 7th Brigade.
In late February 2010, 130 soldiers from the battalion’s ‘A’ Company took over responsibility of the Timor Leste Task Group, replacing 2nd Battalion, The Royal Australian Regiment in East Timor. This Force was rotated back to Australia in June 2010 after a four month deployment and was replaced by ‘B’ Company, 8/9 RAR.
The battalion has also contributed personnel to Operations Slipper, Anode, Pakistan Assist, and was heavily involved in search and rescue efforts during the 2010-2011 Queensland floods, deploying its emergency support force on short notice to Grantham in the Lockyer Valley. As of mid-2011, 8/9 RAR consists of a battalion headquarters, three rifle companies and an operational support company.
The motto of the 8th/9th Battalion, The Royal Australian Regiment is ‘Duty First’.