Kenin grew up in Portand, Oregon. In 1925, he played the violin in George Olsen's orchestra. When Olsen and others left Portland to accept a hotel gig in Los Angeles, Kenin and other members of the orchestra remained at the Portland Hotel to complete the Olsen band's contractual obligations. The next year, Kenin formed his own orchestra, which was hired to be the house band at Portland's Multnomah Hotel. In 1927, the band recorded four sides for the Victor label that became popular enough that they were hired as the house band of the Ambassador Hotel in Los Angeles, where they continued to record for Victor.

Between 1958 and his death, Kenin served as the President the American Federation of Musicians, negotiating contracts on behalf of the 300,000 members of this union with the major television studios and the film industry. He also was a vice president of the A.F.L.‐C.I.O.