Alphonsus John Carroll was born in Mataura, Southland, on 20 April 1895, the youngest of 10 sons of Margaret Kearney, a tailoress, and her husband, Robert Carroll, a mill worker. Both of his parents were born in County Cork, Ireland. Known as Phonse, he was educated at the convent school in Mataura and, when the family moved to a farm near Palmerston North, Glen Ōroua School. The family were committed pacifists, and Carroll was a conscientious objector during the First World War.
As a young man Phonse Carroll worked on the family farm. He also developed a keen interest in horse-racing, and was the owner–trainer of Captain Macky, a jumper who won six races, including the 1916 Lincoln Steeplechase Handicap at Riccarton Racecourse. Captain Macky broke down later that year and in 1917 Carroll turned to rugby, a sport at which four of his brothers had represented Manawatū. One, Mick, had been selected to tour Australia with the 1914 New Zealand team, but withdrew because of business commitments.
Five feet eight inches tall and weighing 14 stone, Phonse Carroll played hooker in the old 2-3-2 scrum formation. He was a member of the Rangiotu Huia club when he represented Manawatū for the first time in 1919, playing in all of the province's seven matches that season. He also played in the North Island team from 1919 to 1921. In 1920, now with the Pirates club, Carroll appeared in one representative fixture and in the inter-island match, before being selected for the All Black team to visit New South Wales. He enjoyed a successful tour, playing in seven of the ten matches, including two of the three key games against the New South Wales state side.
In 1921 Carroll appeared for a New Zealand XV against New South Wales in Christchurch. He played for Manawatū–Horowhenua that year, for a combined Manawatū–Wellington XV the following season, and continued to represent Manawatū until 1924, captaining the team in his last season. In 1922–23, however, he had difficulties with the Manawatū Rugby Football Union over travelling expenses and return of gear. Although he played well in a trial match for the 1924–25 All Black tour of Britain, France and British Columbia, he missed the final selection.
In 1925 Phonse Carroll switched codes and began playing rugby league for the Foxton club. As a former conscientious objector, he may have felt that with returned servicemen becoming more involved in rugby administration, his prospects in top-level rugby were limited. Politically left of centre, and with friends playing league, he was more at home in a game with a strong working-class background.
Carroll quickly won national recognition in his new code, touring Australia in 1925 and England in 1926–27. While the former tour was moderately successful, the latter was a disappointment, with only 17 of the 34 matches won. Even worse, there were constant disputes between co-manager E. H. Mair and seven forwards (including Carroll), who sat out much of the tour. The seven returned home separately, having been given £10 each by English league authorities after claiming they were destitute.
Back home the seven rebel players were banned for life by the New Zealand Rugby Football League; their suspensions were eventually lifted in September 1962. The ban marked the end of Carroll's involvement with league, although he was approached to act as a scout for British clubs – an offer he rejected. He applied to return to rugby union in 1930, but without success. Reinstatement to that code eventually occurred in 1967, when the New Zealand Rugby Football Union was celebrating its 75th jubilee. Despite being banned from rugby, Carroll helped coach the Palmerston North St Patrick's senior club side in the 1930s. However, perhaps significantly, he did not appear in studio photos of the team.
A dairy farmer, Carroll spent the rest of his life on his 100-acre farm, Snake Gully, at Glen Ōroua. From the 1930s until his death, cricket matches were played at the farm each Sunday, with visiting teams competing against the Snake Gully side. He was active in the local branch of the New Zealand Labour Party, especially in the early 1930s, and served as president of the Manawatū Labour Representation Committee for some time.
On 17 July 1940 Carroll married Myrtle Constance Robinson in Feilding. They were to have four sons and a daughter. Two sons, Joe and Jim, played representative rugby for Manawatū, the latter being an All Black trialist and test match reserve; a grandson has also represented Manawatū. Phonse Carroll died in Palmerston North on 1 December 1974, survived by his wife and children.