Walker died Saturday of liver cancer, his personal assistant, Polly Klemmer, told The Associated Press. He had continued to work until just a few weeks ago, making his last concert appearance in Los Angeles in March, Klemmer said Sunday.
He had his greatest success as the guitarist and vocalist for the Walker Brothers, which produced such 1960s hits as "The Sun Ain't Gonna Shine Anymore," "Love Her," "Make it Easy on Yourself" and "My Ship Is Comin' In." While the Beatles and other British groups were remaking the face of rock 'n' roll during the so-called British invasion of America in the mid-1960s, Walker moved from the United States to England instead.
There, he and two other Americans, bassist Scott Engel and drummer Gary Leeds, called themselves the Walker Brothers and each adopted Walker as his surname, although they were not related. They had instant success with their first British recording, 1964's "Love Her," and a string of hits quickly followed.
Walker, who was born John Maus, had begun using the name Walker professionally when he was 17, adopting it, according to some accounts, so he could obtain a fake I.D. that allowed him to play at nightclubs he was too young to legally enter.
He, Engel and drummer Al "Tiny" Schneider, first used the name Walker Brothers when they worked as the house band at the Hollywood nightclub Gazzari's, shortly before he and Engel moved to Britain and joined Leeds.
As part of the Walker Brothers, he toured the world and sold more than 23 million records, according to his website.
The group also appeared on numerous British television shows in the 1960s. He also appeared in the film "Beach Ball," the German music series "Beat Club" and other shows.
Walker, who took up the guitar at age 14, began performing professionally in the late 1950s. By the early 1960s he was a regular at such popular Hollywood clubs as Pandora's Box on the Sunset Strip and on the college circuit.
During those years, he worked with such musicians as Ritchie Valens and Glen Campbell, with producer Phil Spector and songwriters Tommy Boyce and Bobby Hart, who wrote for the Monkees and other groups.