His father, Jim O'Hehir, was active in Gaelic games, having trained his native county to win the 1914 All-Ireland title in hurling.
He subsequently trained the Leitrim football team that secured the Connacht title in 1927 and he also served as an official with the Dublin Junior Board.
O'Hehir never played football, but he enjoyed a distinguished hurling career with the St Vincents GAA club in Raheny.
O'Hehir was accepted and was asked, along with five others, to do a five-minute microphone test for a National Football League game between Wexford and Louth.
Sports broadcasting in Ireland was still in its infancy at this stage, however, O'Hehir's Sunday afternoon commentaries quickly became a way of life for many rural listeners.
In 1947, he faced his most challenging broadcast to date when he had to commentate on the All-Ireland Football Final from the Polo Grounds in New York City.
In 1944, O'Hehir joined the staff of Independent Newspapers as a sports sub-editor, before beginning a seventeen-year career as a racing correspondent in 1947.
as one of O'Hehir's finest moments in racing commentaries and won him great respect for the speed and smoothness with which he picked out the unconsidered outsider.
[citation needed] Buckingham advised O'Hehir that Foinavon's silks had been changed at the last minute as his regular green colours were considered unlucky.
However, in the 1969 Grand National, O'Hehir made a horrendous error stating that eventual winner Highland Wedding had fallen at Bechers Brook (2nd circuit) when a horse called Kilburn fell.
As a result of his influence, O'Hehir secured the broadcasting rights to the closing stages of the All-Ireland hurling and football championships for the new station.
O'Hehir later provided commentaries for other non-sporting events such as the reburial of Roger Casement (who had been executed in 1916) in 1965 and the celebrations marking the golden jubilee of the Easter Rising in 1966.
In 1987 the centenary All-Ireland football final took place and a special series of events were planned on the day at Croke Park.
There was a parade of the 1947 Polo Grounds finalists; however, the biggest cheer of the day was reserved for O'Hehir who was pushed onto the field in a wheelchair by his son Peter.
Oh, what a magnificent save there by Art Foley" – O'Hehir's description of Art Foley's famous save in the final moments of the 1956 hurling final "And Tom Cheasty breaks through with Kilkenny defenders falling around him like dying wasps" – during one of the Kilkenny – Waterford games of the late 1950s or early 1960s "And it looks like there’s a bit of a schemozzle in the parallelogram" – O'Hehir's ubiquitous euphemism for a fight "The greatest freak of all time" – after Mikey Sheehy lobs the ball into the goal while Dublin goalkeeper, Paddy Cullen is arguing with the referee "And it looks as if they were winning the way the Offaly men are just dithering and dawdling there...and here they come.
"And the bare-footed wonder with the ball now" – O'Hehir's description of Babs Keating who played some of the 1971 All-Ireland Hurling Final in his bare feet "And there he is, Alan Lotty.
– O'Hehir's unusual description of Cork's Alan Lotty after he discarded his boots and socks and lost his hurley in a collision with another player "And it is a penalty.