Hunt, 31, was arrested in December last year before pleading guilty on separate charges of possessing a dangerous drug (Alprazolam) and contravening a police direction, fined 300 Australian dollars for each offence.
RA said it found Hunt committed "a low-level breach" of the organisation's player code of conduct.
It fined Hunt 10,000 AUD and handed him a four-match suspension, while he was placed on an illicit drug testing program for 12 months and will participate in any drug treatment and education programs deemed necessary by RA.
However, RA said Hunt had already served the ban given his voluntary stand-down since his arrest.
"We take all matters of off-field behaviour seriously and have conducted a thorough investigation into the events surrounding Karmichael Hunt's arrest in December, and the subsequent court proceedings," RA chief executive Raelene Castle said.
"In arriving at [this] outcome, we've considered the judgement of the court and all the evidence we had available relating to Karmichael's arrest, as well as considering the damage that the very public nature of his arrest and the subsequent speculation has inflicted on the game.
"The penalty handed down to Karmichael also takes into account a previous disciplinary matter for which he was fined and suspended in 2015."
The Reds have made a strong start to the Super Rugby season, winning three of their opening four games.
Photo Getty Images. Caption: Queensland Reds' Karmichael Hunt