The 20-year-old scored five goals in three PL2 matches last month to put Liverpool five points clear at the top of the table after six wins out of six.
His goals included a hat-trick in a 4-2 win over Tottenham Hotspur at Anfield on 22 September, four days after netting both goals in a 2-0 triumph at West Ham United.
He also played in a 1-0 PL2 success against Manchester City and scored in the 1-1 Premier League Cup draw at Charlton Athletic.
The midfielder beat seven other nominees to win the accolade, which was decided by a panel of the Premier League Football Development department after PL2 club managers had nominated the best individual performance from each of their opponents during the month.
Arsenal's Reiss Nelson was the winner for August.