Gardner was a self-taught musician with minimal coaching. He formed the semi-professional New Colorado Band in 1928, and a year later entered the band in a contest at Chelsea Town Hall, and won. He was spotted by the founding editor of Melody Maker magazine, and had secured his first regular professional position later that year. In 1933, Freddy was taken under the wing of Ray Noble and recorded with The New Mayfair Dance Orchestra.
He developed his technique by working in bands led by Sydney Lipton, Billy Bissett, and Bert Firman. As a skilled clarinetist, alto, tenor, and baritone saxophonist, Gardner became a prolific recording session player. He can be heard on numerous recordings by The Four Stars (2), The Six Swingers, Jay Wilbur, Benny Carter, Teddy Foster, Valaida Snow, Ray Noble, Ike Hatch, Mario Lorenzi, and the internationally famous team of pianist Buck Washington and singing tap dancer John W. Bubbles (of Buck And Bubbles).
Gardner led small groups in 1936-37, on the Interstate label, distributed by Interstate Music in East Sussex, England. Toward the end of 1937, he began to be billed as "Freddy Gardner and his Swing Orchestra' with which he made many recordings. The band included such musicians as George Chisholm and Ted Heath. After serving in World War II he was featured as a soloist with Peter Yorke And His Orchestra.
Gardner was tragically felled by a stroke in 1950, and passed away at the age of 39 on July 26, 1950.