Harit, 20, joined the German outfit from Ligue 1 side Nantes in the off-season and the World Cup-bound midfielder proved to be an integral part of their UEFA Champions League qualification.
With three goals and seven assists in 31 Bundesliga games, Harit propelled Schalke to runners-up behind giants Bayern Munich.
The "Rookie Award" is presented by the German league organisers who select footballers who are under the age of 23 at the start of the campaign and at the end of the season, each monthly winner of the award competes for the overall annual prize.
French-born Harit won the U19 Euro 2016 championship with France before switching his international allegiance to the Atlas Lions, the country of his parents birth.
Harit has since won two caps for Herve Renard's side and has been selected for the final 23-man squad set to compete in Russia next month.
Other nominees for the Rookie award included; Jann-Fiete Arp, Tatsuya Ito (both Hamburg), Sébastian Haller (Eintracht Frankfurt), Valentino Lazaro (Hertha Berlin), Benjamin Pavard (Stuttgart), Jadon Sancho and Dan-Axel Zagadou (both Borussia Dortmund).