The Irish Championship of 1947 was held in Cork, for the first time. The format was a 14-player all-play-all, with each provincial union nominating three players, to be joined by the defending champion. In the event, the defending champion, Barney O'Sullivan, played instead at the Hilversum Zonal; Leinster nominated a replacement, and made a fifth nomination, possibly to avoid a bye.

John O'Hanlon, playing in his 21st championship, and 71 years old, was the only former champion competing. John C. Hickey and Con O'Leary were North and South Munster champions, respectively, for 1947, and were joined in the Munster contingent by future Irish champion Austin Bourke. Dr. Michael O'Donnell was the reigning Connacht champion. Paddy Duignan was the Irish Civil Service champion, and also won the Leinster championship in 1946. William Minnis, who along with O'Hanlon and Warwick Nash of Athlone was a veteran of the previous Olympiad team from Buenos Aires 1939, had won the Ulster championship in 1945. Future three-time champion Dónal O'Sullivan was playing in his first Irish championship.

Paddy Duignan took an early lead, winning his first six games, including a second round win against O'Hanlon, and reaching 7½/8. He lost decisively to Warwick Nash in round 9, in the only game that survives, opening up the event. O'Sullivan, after the eventual resolution of all adjournments, also scored 7½ out of his first eight games, while Bourke and Nash scored 7.

The decisive day featured rounds 10 and 11. Duignan beat Kearney in the morning, then defeated O'Sullivan in the evening. Accounts of this crucial game vary a little: “A very equal opening led to a complicated middle game with O'Sullivan (Black) having a slight positional advantage. Duignan's skill was seen to advantage when forcing the exchange of pieces, he turned play into an end game favourable to himself where, after a prolonged struggle, he forced O'Sullivan's resignation” (Cork Examiner) versus “O'Sullivan with the Black pieces chose the Sicilian Defence, and early on from a complicated position lost a pawn, and despite stiff resistance could not prevent the exchanges of pieces by his opponent, who utilised his pawn advantage to win on the 64th move” (Sunday Independent). This left Duignan with 9½/11, followed by Nash on 7½, Bourke and O'Hanlon on 7, each with one adjourned game, and O'Sullivan on 6½, with two adjourned games.

On the final day, Duignan won his morning game against Frank Killeen to make certain of the title, and took a last round draw against the backmarker Pat Diskin to finish on 11/13 for his only Irish championship. Nash took second with 9½, ahead of O'Sullivan on 9. Bourke and O'Hanlon shared 4th and 5th places on 8½.