The 21-year-old full-back currently plays for Newcastle Jets in the A-League and has made 25 appearances this season.
In a statement released by the Jets, Goodwin admitted: "I can't express enough how great an opportunity it is.
"You don't get these chances every day, so for myself to have this chance is something I'm very thankful for.
"I don't have any expectations heading over there. It will be great to learn and experience the game over there."
Two Australians, Adam Federici and Ryan Edwards, are already with the Royals and Goodwin added: "I'm the fittest I have ever been at the moment."