Alan Haworth was drafted by Buffalo with their sixth pick in the 1979 Entry Draft and he made his first appearance as a member of the Sabres during the 1980-81 season. He divided his first two years of professional hockey between Buffalo and Rochester of the AHL. In June 1982, he was traded to the Washington Capitals for draft choices, and he played the next five seasons as a Capitals forward.
He consistently scored more than twenty goals a season during his time in Washington, putting up his personal-best numbers in 1985-86 when he had 34 goals and 39 assists for a total of 73 points in 71 games. In 1987, he was traded to Quebec as part of a multi-player deal and spent his final NHL season as a Nordiques player. From 1988-89 through 1991-92, Haworth played for SC Bern in Switzerland before hanging up his skates and retiring from active play.