2009-10: Scott Arnold led the Brockville Braves with 42 goals in his third season in the Central Junior Hockey League. The Braves finished first in the Robinson Division and reached the playoff finals against Yzerman Division champion Pembroke. Arnold scored 4 goals with 2 assists and had 18 penalty minutes in 13 playoff games. In April he committed to playing college hockey at Niagara in 2010-11.
2010-11: Arnold played 34 games for Niagara University as a freshman. He scored 16 goals with 6 assists and was minus-12 with 51 penalty minutes. Niagara finished second in Atlantic Hockey but was upset by Canisius, 6-3, in the first round of the league tournament.
2011-12: Arnold attended the New Jersey and Calgary development camps over the summer before being diagnosed with testicular cancer in August. After undergoing successful treatment he was able to recover in time for the Niagara season-opener against Michigan and skated in 33 games for the Purple Eagles as a sophomore. Arnold scored 10 goals with 8 assists and was an even plus/minus with 42 penalty minutes. Niagara finished fourth in Atlantic Hockey and lost to RIT in overtime in the conference tournament semifinals. Arnold signed a two-year entry-level contract with the Coyotes in March 2012; foregoing his final two years of college hockey. Arnold practiced with the Coyotes during the playoffs but didn't see any action.