Bill Arnold was born on May 13, 1992 in Needham, Massachusetts. The product of the United States National Development Team Program of the USHL was drafted by the Calgary Flames in the fourth round, 108th overall, of the 2010 NHL Entry Draft.
After Arnoldís one year in the USHL, he would commit to play for the Boston College Eagles of the NCAA. Arnold would play four years with Boston College, including a national championship by winning the 2012 Frozen Four Tournament.
Upon his graduation he would immediately sign his NHL entry level contract with the Calgary Flames where they gave him a shot at the NHL level right away. On April 13, 2014, Arnold made his NHL debut in a 5-1 loss to the Vancouver Canucks. The following season, Arnold would play his rookie season in professional hockey with the AHLís Adirondack Flames.