The 22-year-old defender has signed a three-year deal, with the Club holding the option of a further year, for an undisclosed fee.
McLoughlin, who has represented the Republic of Ireland at U21s level, has been a regular fixture in the Cork City side over the past two seasons.
He joined the Leesiders in the summer of 2017, with the Irish side seeing off competition from clubs in both England and Scotland to claim his signature, and made his debut for the Rebel Army against St Patrick’s in October 2017.
Two accomplished campaigns in 2018 and 2019 have seen McLoughlin establish himself as one of the most exciting prospects in the League of Ireland, with a total of 63 appearances in all competitions – including Champions League and Europa League qualifiers.
Speaking after putting pen-to-paper, McLoughlin said: “The move has been going on for the past couple of weeks now, so to finally get over here and sign – I’m delighted.
“I’m buzzing to be here and to be a Hull City player. I know I’ve still got a lot to learn, but it’s a fantastic opportunity and I’m looking forward to the challenges ahead.”