[2] During his career he worked in swing and dixieland settings with Al Cohn, Eddie Condon, Stan Getz, Gene Krupa, Zoot Sims, Joe Venuti,[3] and often with Bob Wilber and Bobby Hackett.

[4] McKenna's musical style relied on two key elements relating to his choices of tunes and set selection, and the method of playing that has come to be known as "three-handed swing".

The bassline, for which McKenna frequently employed the rarely used lowest regions of the piano, was often played non-legato to simulate a double bassist's phrasing.

Sometimes he also added a guide-tone line consisting of thirds and sevenths on top of the bass, played by the thumb of the left hand.

With his right hand's remaining fingers, he then played the melody, weaving it into improvised lines featuring colorful chromaticism, blues licks and mainstream-jazz ideas.

[5] McKenna often used his left hand to emulate the sound of a rhythm jazz guitarist, playing a four-to-the-bar "strum" consisting of a bass note (root/fifth/other interval), third and seventh.

However, it was a more modern four-beat style, as opposed to stride's two-beat "oom-pah" rhythm (a la Fats Waller).