On 30 June 2017, BBC Wales reported that the two South African teams being dropped from the Super Rugby competition, the Cheetahs and Southern Kings, would be immediately added to Pro12.

[7] Among the prominent departures from the first team squad were Irish international scrum-half John Cooney, who joined Ulster, long-serving prop Ronan Loughney, who retired, and former Springbok Marnitz Boshoff, who departed a year earlier than initially planned for personal reasons.

Incoming players included Australian flanker Jarrad Butler and prop Peter McCabe, who had previously been on loan with the team.

The team also agreed a deal to sign Fiji international Eroni Vasiteri,[8] but the move was called off after he received a nine-week ban for gouging.

The Connacht senior squad for 2017–18 was:[22] Note: Flags indicate national union under World Rugby eligibility rules.

The Connacht academy squad for 2017–18 was:[25] Note: Flags indicate national union under World Rugby eligibility rules.

[48] Connacht's main shirt sponsors were Irish sporting retailer Intersport Elverys, in the second year of a three-year deal.