Borden studied medicine at Harvard University and practiced as a physician for some years in Canning. He was elected in 1874 as Liberal member of the Canadian House of Commons for Kings County and represented this constituency (except for the years 1882–87) until his defeat in 1911. He was knighted in 1902. As minister of the militia, Borden made improvements in training and discipline in the little-developed Canadian forces. With the acquisition of naval establishments at Halifax, Nova Scotia, and Esquimalt, B.C., his department became responsible for developing the Canadian navy and was influential in terminating the practice of appointing a British officer to command the Canadian militia.