Geoffrey Bruce was born in Scotland, into a military family with deep ties to British India. His father, Sir Charles Bruce, was a colonial administrator, and his uncle was General Sir George Bruce. Geoffrey received his education at Wellington College, Berkshire, a prestigious institution that prepared many young men for military careers.

Bruce's military career began during World War I when he was commissioned as a second lieutenant in the Glamorgan Yeomanry, serving in Egypt and Palestine. After the war, he transferred to the British Indian Army, where he participated in the Third Anglo-Afghan War in 1919. For his bravery and leadership, he was awarded the Military Cross in 1921.

Bruce continued to serve in British India during the interwar years, taking part in the North-West Frontier operations from 1920 to 1923. He attended the Staff College, Quetta, from 1927 to 1928, where he studied alongside future military leaders. After furthering his education at the RAF Staff College in Andover, he returned to Quetta as an instructor. In 1937, he was promoted to Commanding Officer of the 2nd Battalion, 6th Gurkha Rifles.

Beyond his military service, Geoffrey Bruce is best known for his mountaineering feats. In 1922, he was part of the British expedition to Mount Everest, where he and George Finch set a world record by reaching a height of 27,300 feet (8,321 meters), just 1,732 feet below the summit. This achievement, using supplemental oxygen, was groundbreaking at the time. Bruce’s efforts were recognised when the team was awarded gold medals at the 1924 Chamonix Winter Olympics.