Like many skaters of the time, Jack Eastwood competed in the singles as well as in the pairs events. In the men’s singles he competed in the 1928 Olympic Winter Games and World Championships, placing eighth at the latter. At home, he placed third at the National Championships in 1927 and 1929.
In the pairs, Eastwood partnered with Maude Smith, later known by her nickname “Jim”. In 1928, they skated to a 10th place finish at the 1928 Winter Olympics, and were 6th at the 1928 World Championships (two years later, they did not manage to improve their performance when they finished 7th). At North American Championships they had their best result placing second in 1933. They reached the Canadian national podium in 1929 and 1933 as runners up to Constance Wilson-Samuel and her brother Bud Wilson.
Eastwood and Smith were third at the 1932 and 1934 Canadian Championships before Smith retired from the sport in 1936. Their only Canadian Championships came in 1926 and 1927 in the fours and in 1936 in the 10-step (with non-Olympian Veronica Clarke), both discontinued events. Eastwood competed one more year with his new partner, non-Olympian Mary Jane Halsted, placing third in the pairs and the fours in 1937.