Although she frequently appeared on television in her latter years, Cannon is best remembered as a film actress, with a lengthy career in British productions from the 1930s to the 1960s.

After early experience at Minnie Everett's School of Dancing in Sydney, Cannon began acting on the stage at the age of four in Madama Butterfly.

She appeared in productions for both the J. C. Williamson and Tait companies – including the early prominent role of Ruth Le Page in Sealed Orders at the Theatre Royal in 1914,[3] and played Baby in an adaptation of Seven Little Australians the same year.

Apart from her usual comedy roles, she gave two dramatic performances, the first in Holiday Camp (1947), playing a pathetic spinster who is lured to her death as a murder victim, and the other as a girl struck dumb by terror, alongside Margaret Lockwood in Jassy (also 1947).

The play featured a number of scenes with the two actresses on the set of Carry On Cabby (her antepenultimate role) with Cannon characterised as being disenchanted with acting and proposing leaving show business.