[3] Born into an Irish family in Burnley, Lancashire,[4] O’Malley sang with Jack Hylton and his orchestra in the United Kingdom from 1930 to 1935.

[5] At the end of 1935, Hylton and O'Malley came to the United States to record with a band composed of American musicians, thus emulating Ray Noble and Al Bowlly.

Other television work from this period includes roles in Spin and Marty film (1955) and serial (1955–57) as the always-faithful ranch steward, Perkins.

In 1959 and 1960, O'Malley portrayed a judge and a newspaper editor in three episodes of the ABC western series The Rebel about a roaming former Confederate soldier.

On January 6, 1959, O'Malley played a priest in the episode "The Secret of the Mission" on the syndicated adventure series Rescue 8.

The same year, O'Malley guest starred on the TV Western Gunsmoke as the title character “Print Asper” (S4E36).

O'Malley was cast as Walter Morgan in the 1959 episode "The First Gold Brick" of the NBC western series The Californians.

In season 3, Episode 10 of the television series Wanted: Dead or Alive, "The Medicine Man", O'Malley played Doc.

In 1960, O'Malley made guest appearances on The Tab Hunter Show, The Law and Mr. Jones, Johnny Midnight, Johnny Staccato, Harrigan and Son, Adventures in Paradise, The Islanders, Going My Way, The Tall Man, and as Jim Phelan on Lawman episode titled "The Swamper."

In the 1966 episode "The Four Dollar Law Suit" of the syndicated western series Death Valley Days, O'Malley played a lawyer.

He made several appearances on Maude between 1973 and 1975; and he performed on other series such as It Takes a Thief, One Day at a Time, Emergency!, Adam-12, The Practice, Three's Company, and Taxi.

In the 1975 episode "You Dirty Rat" O'Malley played Mr. Holliman, the likeable homeless man who fell asleep and spent the weekend in Siegel's department store.