Club

O'Donnell began his club hurling career with Éire Óg in Kilkenny.

In 1947 he lined out in his first championship decider. Tullaroan provided the opposition, however, a 3–10 to 0–13 victory gave O'Donnell a Kilkenny Senior Hurling Championship medal.

A move to Wexford saw O'Donnell join the St Aidan's club in Enniscorthy. In 1952 the club reached the county decider. Horsewood provided the opposition, however, a victory for St. Aidan's gave O'Donnell his first championship medal with his adopted club.

It was the first of three-in-a-row for St. Aidan's, as subsequent victories over Geraldine O'Hanrahan's in 1953 and Horsewood in 1954 gave O'Donnell two more championship medals.

Four-in-a-row proved beyond St. Aidan's, however, the club bounced back in 1956 with O'Donnell winning a fourth championship medal in Wexford. Once again St. Aidan's went on to dominate the club championship and secured four successive championship titles, bringing O'Donnell's overall medal tally to seven.

Inter-county

O'Donnell first played at inter-county level with the Kilkenny junior team in 1946. Unable to dislodge Pat "the Diamond" Hayden from the full-back position on the team, he won a set of Leinster and All-Ireland medals as a non-playing substitute.

Success in this grade earned O'Donnell a call up to the Kilkenny senior team. Once again, Hayden stood in the way of O'Donnell being picked on the starting fifteen. In spite if this he was an unused substitute when Kilkenny captured the Leinster crown. O'Donnell was a substitute again when Kilkenny later defeated Cork by 0–14 to 2–7 in, what has been described as, the greatest All-Ireland final of all-time. In spite of being a named substitute, he received no All-Ireland medal. Kilkenny had a panel of twenty-two for the game but only received twenty-one All-Ireland medals. O'Donnell was deemed the last man, a decision which rankled with him for the rest of his life. He later said: "Kilkenny, my native county, still 'owes' me an All-Ireland senior hurling championship medal – the one I never got when I was a member of the panel of Kilkenny's championship of 1947. I was never bitter about it, but I always felt very disappointed about it. It was my first All-Ireland senior one."

O'Donnell soldiered with the Kilkenny team for another few years without any hope of breaking onto the starting fifteen.

A move to Wexford saw him declare for their senior hurling team in 1951. He made his debut at full-back against Dublin that year, before later lining out in his first provincial decider. A 3–12 to 4–3 defeat of Laois gave O'Donnell his first Leinster medal. A subsequent defeat of Galway saw Wexford qualify for the All-Ireland final on 2 September 1951, their first appearance in the decider since 1918. Tipperary provided the opposition as they aimed to secure a hat-trick of championship titles for the first time in over half a century. Nicky Rackard, Wexford's goal-scoring machine, was nullified by Tipp goalkeeper Tony Reddin, while Séamus Bannon, Tim Ryan and Paddy Kenny scored key goals which powered Tipp to a 7–7 to 3–9 victory.

Wexford faced back-to-back provincial decider defeats over the next two years, however, in 1954 the team regrouped. A huge 8–5 to 1–4 defeat of Dublin gave O'Donnell a second Leinster medal. Cork provided the opposition in the subsequent All-Ireland final on 5 September 1954 and, once again, it was an historic occasion as Cork's Christy Ring was provided with an opportunity of capturing a record-breaking eighth All-Ireland medal. A record attendance of 84,856 packed into Croke Park, and Wexford had the reigning champions and three-in-a-row hopefuls rattled. O'Donnell's side had a 1–3 to 0–5 lead at the interval, however, he was forced to leave the field with an injured collarbone after a clash with Ring. Wexford still had a four-point lead at the three-quarter stage, however, Johnny Clifford scored a vital goal to secure a 1–9 to 1–6 victory for Cork.

In 1955 O'Donnell was honoured with the captaincy, as Wexford continued their provincial dominance. He collected a third Leinster medal that year following a 5–6 to 3–9 defeat of Kilkenny in a replay of the Leinster final. Galway, who got a bye into the All-Ireland final without picking up a hurley, provided the opposition on 4 September 1955. A Tim Flood goal nine minutes from the end clinched a 3–13 to 2–8 victory for Wexford and a first All-Ireland medal for O'Donnell, while he also had the honour of lifting the Liam MacCarthy Cup. It was Wexford's first All-Ireland triumph in forty-five years.^[4]

Wexford continued their dominance in 1956. A 5–9 to 2–14 defeat of Tipperary gave O'Donnell a first National Hurling League medal. The subsequent championship campaign saw Wexford reach the provincial final once again. A narrow 4–8 to 3–10 defeat of Kilkenny gave O'Donnell his fourth Leinster medal. Galway fell heavily in the All-Ireland semi-final, allowing Wexford to advance to an All-Ireland final meeting with Cork on 23 September 1956. The game has gone down in history as one of the all-time classics as Christy Ring was bidding for a record ninth All-Ireland medal. The game turned on one important incident as the Wexford goalkeeper, Art Foley, made a miraculous save from a Ring shot and cleared the sliotar up the field to set up another attack. Nicky Rackard scored a crucial goal with two minutes to go giving Wexford a 2–14 to 2–8 victory.^[5] In spite of Cork's loss Wexford's O'Donnell]] and Rackard, in an unparalleled display of sportsmanship in any game, raised Christy Ring onto their shoulders and carried him off the field. Wexford had won the game and O'Donnell had collected his second All-Ireland medal but there was no doubt in their minds that the real hero was Ring.^[6]

Two year later in 1958 O'Donnell added a second National League medal to his collection following a 5–7 to 4–8 defeat of Limerick.

In 1960 O'Donnell was captain once again, and Wexford were back in the provincial decider. A narrow 3–10 to 2–11 defeat of Kilkenny gave O'Donnel his fifth Leinster medal. The All-Ireland decider on 4 September 1960 saw Tipperary provide the opposition. A pitch invasion at the end resulted in much confusion, however, goals by Mick Hassett and Oliver McGrath gave Wexford a merited 2–15 to 0–11 victory. It was O'Donnell's third All-Ireland medal and his second time lifting the Liam MacCarthy Cup.

After surrendering their titles the following year, Wexford were back in 1962. Another narrow 3–9 to 2–10 defeat of Kilkenny gave O'Donnell a sixth Leinster medal. The All-Ireland final on 2 September 1962 was a repeat of 1960 with Tipperary, the reigning champions, lining out in opposition. Wexford, however, were not the force of old and the side got off to possibly the worst start ever by a team in a championship decider. After just ninety seconds the Leinster champions were down by two goals, courtesy of Tom Moloughney and Seán McLoughlin. The game, however, turned out to be much closer than people expected. Tipp eventually secured the win on a score line of 3–10 to 2–11. O'Donnell retired from inter-county hurling following this defeat.

Inter-provincial

In 1956, having previously been told that there was no place for him on the team, O'Donnell took over the full-back position on the Leinster inter-provincial team. That year he captained his province to victory, and was accompanied on the team by nine of his fellow Wexford players. He continued to play with Leinster until 1961, however, Munster were the dominant force in the Railway Cup at the rime.