Following his participation in the 2015 Rugby World Cup, MacGinty was signed by Connacht for the 2015–16 Pro12 season. Connacht head coach Pat Lam said the province had been following MacGinty since the Pacific Nations Cup earlier in the year. MacGinty made his domestic debut for Connacht appearing off the bench in their 33–19 win over Benetton Treviso on 6 November 2015. MacGinty made his European debut on 14 November 2015 in the first match of the 2015–16 Challenge Cup, starting at fly-half and scoring nine points. MacGinty led Connacht to a 28–23 bonus point win over Edinburgh in March 2016 and "controlled matters expertly" to manage Connacht's fifth consecutive win and maintain first place in the Pro12.