Hughes has backed Johnson to come back stronger from the cruciate ligament injury that will see him miss the majority of the season.
"He was playing exceptionally well at the time and had been in previous games so to lose his experience and ability is a blow to us," he told the club's official website, qpr.co.uk.
"People understood why I wanted to bring AJ to the club. He has got fantastic energy and you need those types of players in your squad. He is mentally a very, very strong character. He has been through long-term injuries before and always comes back stronger and I have no doubts that he will do the same again.
"He will get the best treatment and best support from the medical staff here and we will make sure we get him back as quickly as possible without ever compromising him.
"We will make sure he is fit and well when he returns."