3 RAR was initially formed on 20 October 1945 as the 67th Battalion. The battalion was intended for occupation duties as part of the British Commonwealth Occupation Force in Japan and was formed from volunteers from the 3rd, 6th, 7th and 11th Australian Divisions. The battalion was redesignated the 3rd Battalion of the Australian Regiment upon the regiment's formation in November 1948. The 'Royal' prefix was appended in March 1949.
The 67th Battalion arrived in Japan as part of the Australian 34th Brigade in February 1946. As with the rest of the occupation force, the battalion did not encounter any significant resistance or civil unrest. The Australian force in Japan was gradually downsized, with 3 RAR being the only Australian battalion left in the country at the outbreak of the Korean War.
3 RAR was rapidly committed as Australia's main land force contribution to the United Nations forces in the Korean War. After a period of intensive training and reinforcement in Japan, the battalion arrived in South Korea in late September 1950. The battalion formed part of the 27th Commonwealth Brigade and took part in the United Nations offensive into North Korea and the subsequent retreat into South Korea following the Chinese offensive in the winter of 1950–51. In October 1950, the battalion distinguished itself at Chongju during the UN northward advance to the Yalu River. Commanded by Lieutenant Colonel Charles Green, it attacked and captured a large North Korean defensive line in a combined arms operation with tanks and artillery. Green was later killed in action. It was one of three units to receive the US Presidential Unit Citation after the Battle of Kapyong, that was fought between 22 and 25 April 1951.
In July 1951, Major Archer Denness briefly commanded 3 RAR between the departure of Lieutenant Colonel Bruce Ferguson and the arrival of the new commanding officer, Lieutenant Colonel Frank Hassett. Over the period 3–8 October 1951, 3 RAR fought the Battle of Maryang San, which is widely regarded as one of the Australian Army's greatest accomplishments of the Korean War. 3 RAR remained in Korea until the war ended in 1953, sustaining total casualties of 231 men killed. Upon return to Australia in 1954, 3 RAR was based in at Ingleburn and Holsworthy Barracks, in New South Wales.
The next major conflict that 3 RAR was involved in was the Malayan Emergency. The Australian Government first committed a battalion in 1955 to assist Malayan Government counter incursion of Communist Terrorists (CTs). However, it was not until October 1957 that 3 RAR arrived in theatre; it then commenced a period of acclimatisation at the FARELF Training Centre Kota Tingi (later to become the Jungle Warfare School). 3 RAR then moved to company base camps at Kuala Kangsar (BHQ), Lasah, Sungei, Siput, Penang and Lintang. The unit was engaged in anti-communist terrorist operations in northern Malaya. Operations began in November 1957 and as a result many terrorist camps and food dumps were located and destroyed. 3 RAR was credited with killing 14 terrorists and was responsible for the capture of 32 others. 3 RAR casualties over the two years were two wounded and four non-battle casualties. Upon return to Australia, 3 RAR established itself at Enoggera Barracks, Brisbane. It remained there for four years during which time it carried out routine training and barracks duties and was organised on the Pentropic establishment, with five rifle companies and an enlarged headquarters.
3 RAR also served in Malaysia and Borneo during the Indonesia-Malaysia Confrontation and was involved in a series of highly successful cross-border missions under Operation Claret. During these operations the battalion had four major contacts with Indonesian forces on the Sungei Koemba river, at Kindau and again at Babang between May and July 1965. During these operations the battalion lost three men dead and five wounded. 3 RAR moved into Woodside Barracks, South Australia, officially occupying Kapyong Lines at Woodside, on 14 October 1965.
3 RAR served two tours in South Vietnam, the first during 1967 and 1968 saw the battalion stationed in Phuoc Tuy Province. The battalion took part in several operations and was involved in mine clearing, counter mortar and rocket tasks and reconnaissance in force operations. As the ready reaction force at the 1ATF base 'A' Company 3 RAR was responsible for clearing and securing the nearby provincial capital of Ba Ria (Phuoc Le) during the Tet Offensive of February 1968. The battalion was then committed to Operation Coburg in February and March. During 26–28 May 1968, 3 RAR, while stationed at FSB Balmoral in a battalion defensive position, withstood two determined assaults by regimental sized units of the North Vietnamese Army during the Battle of Coral–Balmoral. During its first tour of Vietnam the battalion lost 24 killed and 93 wounded. In 1971 the battalion returned to Phuoc Tuy Province. During the second tour the battalion took part in several actions before returning to Australia by the end of 1971 after an eight-month tour. During these operations 3 RAR lost four killed and 27 wounded.
A move to Holsworthy Barracks, Sydney, contemplated since returning from operations in South Vietnam, was conducted at the end of 1981. In December 1983, the battalion assumed responsibility for the Australian Army's conventional Airborne forces capability (previously, D Company 6 RAR had maintained an airborne company). In 1985, the battalion was granted permission to wear the dull Cherry beret, common to all parachute units worldwide, and to wear parachute wings identical to those worn by the 1st Australian Parachute Battalion during the Second World War. From 1989, 3 RAR formed the main combat elements of the Parachute Battalion Group, which also included an engineer troop, signals detachment, artillery battery, and medical support, including a parachute surgical team. Attached in direct support, A Field Battery, Royal Australian Artillery was equipped with 105-mm L118 Hamel guns.
3 RAR played a key role in the Australian-led International Force for East Timor (INTERFET) in 1999. The battalion arrived in Dili by sea on 21 September and was initially responsible for the city, before later securing the enclave of Oecussi. 3 RAR returned to Australia in February 2000. It served a second six-month tour of East Timor in 2002. In May 2006, the 3 RAR Battalion Group was deployed to restore order to East Timor as part of Operation Astute. An online company group was deployed at short notice in February 2007 for four months and replaced by a second company group in June 2007 for seven weeks. 3 RAR deployed again to East Timor in 2008 as the Timor Leste Battle Group (TLBG), undertaking operations to apprehend the rebels that attempted to assassinate President José Ramos-Horta.
3 RAR deployed to the Solomon Islands on Monday 24 January 2005 to reinforce the military component of Regional Assistance Mission to Solomon Islands (RAMSI). The 3 RAR company of soldiers consisted of approximately 100 personnel to provide added support to the local and Australian Federal Police in enforcing the rule of law and restoring order in the Solomon Islands. The soldiers tent lines at RAMSI base were named the "Private Jamie Clark Lines" in March 2007 after the accidental death of Clark in March 2005. Renewed violence in March 2006 again saw a company group deploy to the capital Honiara, returning to Australia in May 2006.
In late 2003, 3 RAR was warned to provide a Company Headquarters and a four rifle section platoon for security duties in Iraq on Operation Catalyst. A Company was subsequently deployed to Baghdad from December 2003 to May 2004. It provided specific local protection to the Australian Diplomatic Mission in Baghdad as part of the Security Detachment (SECDET). On 13 April 2004 SECDET elements were involved a very successful contact when an ASLAV engaged a mortar base plate that was firing on the Green Zone. From February 2006 until March 2007 the battalion returned companies to Baghdad as SECDET IX and SECDET X. Both tours were eventful with several contacts, a rocket attack that injured four soldiers, and the accidental death of Private Jacob Kovco in April 2006—Australia's first casualty in Iraq and the subject of intense media attention.
2008 saw the battalion deploy a company group to Uruzgan Province, Afghanistan as the Security Task Group (Combat Team Dagger) component of the Reconstruction Task Force 4 (RTF-4) during Operation Slipper. Highlights of the deployment include the establishment of a Patrol Base in the Baluchi Valley, and the short-notice, high-priority deployment beyond the RTF Area of Operations to construct key bridges over the Andar and Moqur Rivers in Zabul and Ghazni Provinces, along the highway connecting Kandahar and Kabul. 3 RAR formed the basis of a battle group that was deployed to the country again in 2012 tasked with mentoring the Afghan National Army 4th Brigade, 205th Corps, before handing over to 7 RAR in November.
On 31 August 2011, 3 RAR relinquished the parachute role becoming a light infantry battalion. In early 2012 it relocated to Lavarack Barracks, Townsville, under 3rd Brigade. The battalion currently consists of:Battalion Headquarters
3 Rifle Companies – 'Alpha', 'Bravo' and 'Charlie'
3 RAR holds the following alliances:United Kingdom – Scots Guards
United Kingdom – The Queen's Royal Hussars (Queen's Own and Royal Irish)
The battalion has received the following battle honours:Korean War: Pakchon; Uijongbu; Chuam-ni; Maehwa-san; Kapyong; Kowang-San; Maryang-San; Korea 1950–1953; Sariwon; Yongju; Chongju.
Vietnam War: Vietnam; Bien-Hoa; Coral-Balmoral.