Deacon used the bass as a lead and rhythm instrument. Some of his bass lines, such as „The Millionaire Waltz”, „I’m Going Slightly Mad” or „You’re My Best Friend”, granted his technique an affinity with Motown’s lead style basslines. Some of Queen’s songs, such as „Dragon Attack”, „Another One Bites the Dust”, „Don’t Try Suicide” or „A Kind of Magic”, feature the bass as the main instrument. When performing with Queen, Deacon delivered a highly technical style, with numerous runs, walking bass lines and tight quick note changes. Deacon mainly used his fingers, though sometimes he did use a pick. He generally did not play with a floating thumb, and occasionally played with his thumb itself.
A trademark of Deacon’s playing are his bass runs. In a 1975 review of Sheer Heart Attack, the reviewer wrote: „Only at the end would a new initiate to Queen recognise John Deacon’s unmistakable trademark: the bass runs under the fade are as fast and facile as any to be heard. The least well known musician in Queen is one of his rock generation’s most able.”