He competed in rowing at the 1930 Empire Games, winning gold in the coxed fours, and at the 1932 Summer Olympics, becoming one of the first two Māori Olympians.

[1] His father, also called Jack, played rugby for the New Zealand Māori team, as did his brothers Manny and Enoka.

[3] At the 1934 national rowing championship regatta in Picton, Macdonald was a member of the winning Wairau four and finished second in the pairs final.

[9] He again rowed in the Wairau four at the national championships in Auckland the following year, but the crew was unable to defend its title, finishing outside the first three.

[10] Following the end of World War II in Europe, Macdonald put together a four to represent the Royal New Zealand Air Force (RNZAF) at the Shepperton regatta in July 1945.

[13][14] A week later at Weybridge, the New Zealand Services eight was beaten by Barnes in the first heat, with the RAAF crew winning the final over Gladstone.

[19] Macdonald played a "slashing game",[20] scoring three tries in his team's second defence of the Ranfurly Shield, against Wanganui, with the holders running out the winners by 25 points to 6.

[23][26] George Nēpia believed that Macdonald should have been an automatic selection for the All Blacks team to tour the British Isles and Canada in 1935–36.

During World War II, Macdonald was reinstated to rugby union[24] and he played for various forces teams in England.

On 17 October 1942 he appeared for the RNZAF team in a match against Guy's Hospital, and reportedly gave a "brilliant display", scoring two tries and a conversion, as the New Zealanders won 11–0.

[28][29] Two weeks later, he again turned out for the RNZAF team, this time against the Welsh Guards at Richmond, kicking a conversion in his side's 8–6 victory.

Macdonald started the game on the wing but moved into centre after the RAF captain went off injured after 25 minutes.

[35] Playing at full-back, Macdonald missed two penalty kicks at goal as the RNZAF was beaten by the RAAF 3–0 on 11 March 1944.

[36] On 15 April 1944, Macdonald played full-back for the Māori team in a "Maoris v Pakeha" match at the Richmond Athletic Ground, with the Pākehā running out the winners by 13 points to 11.