He was a reporter for Drum magazine until 1962 and then left to work for The World, returning to Drum in 1974. He wrote the regular "Bugs" column, which was humorous and satirical, featuring discussions and conversations between two bed bugs. He also wrote the "On the Beat" column.
Motsisi's style borrowed heavily from that of Damon Runyon, using "Americanese" and Tsotsitaal (local township slang). The stories he wrote were based on his extensive knowledge of the Sophiatown shebeen culture, depicting a variety of township types, such as Aunt Peggy, the shebeen queen, and a variety of rogues including Kid Playboy and Kid Hangover.
Motsisi also contributed to The Classic, a journal edited by a fellow Drum journalist Nat Nakasa.
The Drum Decade  contains a number of articles by Motsisi, including:
- "If Bugs Were Men"
- "Johburg Jailbugs"
- "On the Beat" [Kid Hangover]
- "On the Beat" [Kid Playboy]
- "On the Beat" [Kid Newspapers]
- Casey & Co: Selected Writings of Casey "Kid" Motsisi, edited by Mothobi Mutloatse, Ravan Press, 1978, ISBN 0-86975-088-7
- List of South African writers
- Mike Nicol, Good-Looking Corpse: World of Drum - Jazz and Gangsters, Hope and Defiance in the Townships of South Africa, London: Secker & Warburg, 1991. ISBN 0-436-30986-6