His early prowess in the round ball code resulted in being selected in the State Schoolboys soccer team.

In 1928 he was invited to play with the North Adelaide juniors, where he demonstrated some talent at marking and goal kicking, winning the best and fairest award.

Shortly after becoming the first SANFL player to kick 100 goals in a season, Farmer suffered the shock loss of his brother Elliott on 5 September when, on the way home, their motorcycle collided head-on with a truck on Frome Road.

[2] Both brothers were thrown from the vehicle, with Elliott suffering severe head injuries while Ken sustained a sprained ankle.

Farmer played in the winning 1930 Grand Final side despite the great personal distress of his brother's death weeks earlier.

His performances, especially against Victoria, attracted the attention of several Melbourne-based clubs who made offers for his signature, but he never accepted.

[5] Farmer's playing career ended during World War II when he went into the RAAF, where he served as a sergeant from April 1942 to July 1946.

[6] Although Farmer's reputation as a legend of Australian rules football rests on his playing achievements, his success as a coach is often underrated.

After losing to Port Adelaide in the 1951 SANFL Grand Final, Farmer decided to retire, but upon being inundated with requests to continue, informed the club he would coach for one more season.

[8] In the lead-up to the 1952 SANFL season, while waiting for official clearance to resume coaching duties, Farmer shared with the Adelaide press that he believed the two main positional weaknesses that had prevented North Adelaide from winning the premiership in 1951 was in the roving and goal kicking department, and he had identified some country footballers to try out for the positions.

Farmer holds the equal record for most goals kicked in a SANFL or elite match with 23.6 against West Torrens, out of his side's score of 26.11.

In 1980, the Ken Farmer Gates were dedicated on the eastern side of North Adelaide's home ground, Prospect Oval.