Connacht Rugby is one of the four professional provincial men's rugby teams from the island of Ireland, based in Galway. Connacht competes in the United Rugby Championship and the European Rugby Champions Cup. The team represents the IRFU Connacht Branch, which is one of four primary branches of the Irish Rugby Football Union (IRFU), and is responsible for rugby union throughout the geographical Irish province of Connacht.

Connacht plays its home games at The Sportsground, which currently holds 6,126 spectators and can be expanded to 8,129. Connacht play in a predominantly green jersey, shorts and socks. The Connacht Rugby crest is a modified version of the provincial flag of Connacht and consists of a dimidiated eagle and an arm wielding a sword.

With the province containing just over 8% of the total Irish population, Connacht has a much smaller base of rugby union players to choose from than the other three provinces. This player base is also affected by the relative popularity of Gaelic Athletic Association sports such as hurling and Gaelic football. In the early years of professionalism, it was suggested that the Connacht team as a professional entity should be wound up, and fans had to demonstrate to save the province. However, rugby union in Connacht has expanded significantly with increased ticket sales and stadium expansion, in particular since its first season competing in the Heineken Cup.

Through the efforts of the Connacht Branch and the support of the IRFU, the province has experienced growth, increasing its underage and schools participation through initiatives such as the Grassroots to Greenshirts campaign. Connacht enjoyed their most significant senior success in 2016, when they defeated fellow Irish province Leinster in the 2016 Pro12 Grand Final to win the competition for the first time. In 2025, while their home stadium in Galway, The Sportsground, was partly closed for expansion works, Connacht agreed to move one URC match against Munster to MacHale Park, a 25,000 seat Gaelic Athletic Association stadium in Castlebar, County Mayo. The match sold out in the space of two days and became the largest home attendance for a Connacht Rugby game in history.

While the senior men's team is most commonly associated with the Connacht Rugby brand, the province also organises a developmental 'A; side, which plays under a modified version of the brand. Before the creation of the Celtic Cup, the Connacht Eagles competed in the British and Irish Cup.

The provincial union also supports a senior women's team under the same Connacht Rugby branding, which takes part in the IRFU Women's Inter-Provincial Series and the Celtic Challenge under a combined Clovers branding with Munster Rugby.

The Connacht Branch of the Irish Rugby Football Union was founded on 8 December 1885, and along with it the provincial team. The branch was formed to compete with the Leinster, Munster and Ulster branches, which were founded in 1879, and whose teams had been formed in 1875. There were six teams represented at the meeting in Dublin that founded the Connacht Branch. These were Ballinasloe, Castlebar, Galway Town, Galway Grammar School, Queen's College Galway and Ranelagh School Athlone. Galway Grammar and Ranelagh have both closed since, while Galwegians was formed out of Galway Town in 1922. Ballinasloe merged with Athlone to form Buccaneers in 1994, but has since been reestablished as an independent club. Castlebar and Queen's College (now NUI Galway) are the only two founding clubs to have remained active without interruption since the branch was founded. The province is currently made up of 25 senior clubs.

Cape Town-born Henry Anderson was the first Connacht player to receive an Ireland cap, making his debut against England on 14 February 1903. Anderson later went on to be one of the founders of Galwegians, and became the first Connacht branch representative to serve as president of the Irish Rugby Football Union (IRFU). Sligo-born Aengus McMorrow followed in his footsteps to become the first Connacht native player to represent Ireland in 1951. Ballinasloe man Ray McLoughlin was the first Connacht player to captain Ireland, when he led the team in the 1965 Five Nations Championship. McLoughlin also became the first Connacht representative for the Lions when he took part in the 1966 tour to Australia and New Zealand, though he was playing his club rugby for Gosforth in England at the time. Ciaran Fitzgerald became the first Connacht man to captain the Lions when he was chosen by Jim Telfer to lead the 1983 tour to New Zealand.