As a boy, Karl Kaspar Keffer spent most of his time on the Toronto Golf Course close to his home. He worked part time as a caddy and played baseball and hockey. He worked for a while in a candy factory but a boiler blew up and that ended his candy career. He played senior hockey until 1908 when he received a skate-blade foot wound which bothered him the rest of his life.

In 1906, he became a professional golfer at the Toronto Golf Club under the tutelage of George Cumming and won the Canadian Open Golf Championships held at the Toronto Golf Club in 1909 and 1914 and was runner-up along with R.T. 'Bobby" Jones and J.M. Barnes in 1919 at the Hamilton Golf Club.

To this day, Karl Keffer is the only Canadian-born winner of the Canadian Open Golf Championship.

After a year's service as an assistant professional at the Albany Country Club in Albany, N.Y., Karl became the Head Professional at the Ottawa Golf Club in 1911 and remained there throughout his career. The Ottawa Golf Club was given the "Royal" designation in 1912.

He was a founding member of the Canadian Professional Golfers' Association in 1911, its Secretary-Treasurer 1914-1928, Captain from 1934-1937 and President from 1938-1943. He would spend his summers at the Royal Ottawa Golf Club in Aylmer, Québec, and his winters as the pro at the Jekyll Island Golf Club in Jekyll Island, Georgia, USA. He also won the Manitoba Open in 1919 and the Québec Open in 1926.

Karl Keffer married Eveline Freeman in 1913 and their son Howard Franklin Keffer was born on November 25, 1914. From 1916 to 1919, Karl was a soldier in WWI (Sapper in the Royal Canadian Engineers). He was primarily a runner of messages between the trenches. He was influential in getting many young men to join the fight by writing letters in newspapers and to companies and associations, including the Canadian Golf Association. Sadly, while Karl was in France, Eveline was stricken by the influenza pandemic which was sweeping the world in 1918 killing millions of people.

Karl Keffer was also renowned for his club-making ability as well as his golf course design capabilities and his hickory-shafted golf clubs are treasured by collectors.

On October 14, 1929 Karl Keffer was awarded an Honorary Membership by the Royal Ottawa Golf Club for his "faithful and meritorious service". This was a rare honor for at the time the only other Honorary Memberships awarded to golf professionals were to George Cumming of the Toronto Golf Club and Charlie Murray of the Royal Montreal Golf Club.

Karl Keffer continued to serve as a consultant with the Royal Ottawa Golf Club after his retirement in 1943. In the Royal Ottawa's Captain's Book for 1955, there is a hand-written record: "October 22nd, Karl Keffer passed away... a great golfer, sportsman and gentleman."

Karl Kaspar Keffer was inducted posthumously into the Canadian Golf Hall of Fame in 1986, the Golf Ontario Hall of Fame in 2000 and now the Québec Golf Hall of Fame on June 29, 2016.