The company had announced in July that David de Mardt would take up the post on September 1, but he subsequently decided to leave Pernod Ricard for family reasons.
O’Flynn is currently managing director for Ireland with Pernod Ricard’s Irish Distillers division, a position he took on only in July.
He takes up his new post – originally made vacant by the departure of Jean-Manuel Spriet to head up Pernod Ricard’s Korean business - on October 17.
John Leburn will leave his position as finance and development director for Pernod Ricard UK on November 1, to become chief financial officer for the group’s Corby Distilleries operation in Canada.
Pernod Ricard UK finance director Julia Massies will assume full responsibility for the UK firm’s finance function.