Farrell was a rugby league footballer with a long sporting career. He rose through the ranks to become "The Greatest Bluebag of them all." Graded in 1936, he made his début for the Newtown Rugby League Football Club's first-grade team in the 1938 NSWRFL season. He played his entire New South Wales Rugby Football League premiership career of over 250 games with the Newtown club. He made his state representative debut for New South Wales against Queensland in 1939 and went on to play thirteen career matches for his state. He became captain of the club in 1942, leading them to victory in the 1943 NSWRFL season Premiership Final against North Sydney. One of Farrell's closest and lifelong friends, Frank Hyde, was his opposing captain that day.