Rugby union football has been played for over 100 years in Canberra and the surrounding region with the British Lions opening their 1899 Australian Tour with a match in Goulburn.  However, it was not until 1938 that the ACT Rugby Union was formally established with University, Easts, RMC and Norths playing in the inaugural competition.  The ACT fielded their first representative side that same year against the All Blacks, during their nine-match undefeated tour of Australia.  The ACT lost 56-5.

The first international victory for the ACT came in 1973 when they defeated Tonga 17-6.  Five years later the ACT had their most memorable international victory defeating Five Nations Champions, Wales, at Manuka Oval.  After trailing 6-16 at half time, the ACT staged a memorable comeback and won with a penalty goal in the dying minutes to Dominic O'Connell, in front of an estimated crowd of 10,000.

One of the most satisfying wins for the ACT came in 1994 when they soundly defeated NSW at Concord Stadium, 44-28.  This match set the platform for the ACT to be included in the expanded NSW club competition the following year.  A solid performance by the Canberra Kookaburras in their inaugural year led to the ACT's inclusion in the first Super 12 tournament in 1996 as the third Australian provincial team, the ACT Brumbies.

Under the guidance of coach, Rod MacQueen, the ACT Brumbies finished fifth in their first Super 12 season, and then lost to the Auckland Blues in the 1997 final.  Eddie Jones took over the coaching duties in 1998 only to see the team finish tenth.  The Brumbies stepped up a gear in 1999 to narrowly miss out on the finals finishing fifth and then in 2000 hosted the Super 12 final against the Crusaders from New Zealand only to lose by a point, 20-19 at a bitterly cold Bruce Stadium.

2001 saw the ACT Brumbies win the Super 12 Championship against the Sharks from South Africa and become the first team outside New Zealand to win the competition.  The Brumbies also played host to the British Lions at Bruce Stadium, only to lose in the last play of the match, 30-28.  David Nucifora took over from Eddie Jones as Head Coach for the 2002 season and guided the team to their third successive Super 12 final appearance, only to lose to the Crusaders 31-13 in Christchurch.  In 2003 the Brumbies were knocked out of the semi finals by eventual Champions the Blues from Auckland and then went on to defeat Fiji and Tonga in Canberra in June.

2003 also saw four Rugby World Cup matches come to Canberra involving Italy, Wales, Tonga and Canada.  More than 80,000 people attended the four matches over 10 days, with Rugby being the toast of the town during the months of October and November.

Coach David Nucifora and newly-appointed Captain Stirling Mortlock led a Brumbies team containing several ‘unknowns’ to finish six points clear on top of the 2004 Super 12 table, unearthing a new breed of Super 12 and Wallabies stars along the way.  The Brumbies hosted the Crusaders in the 2004 Super 12 Final, winning the championship in emphatic style 47-38 in front of a record crowd of 28,753 at Canberra Stadium.

The 2004 off-season delivered major news and a change in the structure of the ACT Rugby Union. A constitutional reform was passed to expand the territory of the ACT Rugby Union to incorporate the Far South Coast and Southern Inland Unions. The ACT Rugby Union was renamed the ‘ACT and Southern NSW Rugby Union from November 2004. The team name ‘ACT Brumbies’ was changed to ‘Brumbies Rugby’ and a new identity was launched to reflect the expanded region of the Brumbies.

Local product Laurie Fisher began his tenure as head coach of the Brumbies in 2005, leading the team to an unbeaten start in the first month of the competition before a record injury toll crushed the Brumbies finals hopes. Nine players made their Super 12 debut in 2005, while the Brumbies missed out on a finals berth for the first time since 1999 to finish fifth. Off the field, the Brumbies celebrated ten years in the Super 12, hosting a tenth anniversary gala dinner to present 81 Brumbies players with their individual number in order of their debut for the team since 1996.