The 32-year-old Brazilian joined the Italian giants from Chievo in 2005 and has established himself as one of the best goalkeepers in the world.
"I will leave Inter," he told Brazilian network Rete Globo. "I want to thank everyone for these seven wonderful years. I would like to be on the pitch before Inter-Roma to hug all the fans.
"I choose to join QPR because I think I will play more there than at Inter and the Premier League is watched worldwide."
Julio Cesar further shed light on why he decided to leave Inter after seven years.
"I am a bit surprised, but I am delighted to have been given the opportunity by QPR to come to London, learn English and play in the Premier League," he told Sportv News.
"It all started during my summer vacation when Inter suggested that I reduce my salary. No player in my situation would have done that.
"I am not a hypocrite and I can talk openly about this. It became a tough situation for both parties. I then spoke to my representative and I thought this was a good choice."
Julio Cesar won Serie A five times with Inter, the Coppa Italia three times and the Champions League once.