The versatile defender has signed a four-and-a-half year deal with the Loftus Road club for an undisclosed fee, joining Taye Taiwo as a new face at the London club.
Onouha has spoken of his admiration for Hughes, who he worked with at City, and is eager to get started with his new employers.
“This was the right time for me to join a club like QPR,” he told the club’s official website.
“The manager obviously played a massive factor in my decision to come here. I’ve worked with him before and he always wants players around him who are open and honest.
“He wouldn’t have come here if he didn’t believe that there was a squad of players here that can achieve the goals he has.
“The ambition of the owners was really appealing.
“This is my club now and I’ll give everything to help us succeed,” he stated.
Onouha will be charged with shoring up Rangers’ vulnerable rearguard, and is in line to make his debut against Chelsea in the FA Cup on Saturday.
By Gareth McKnight