The France international, who almost joined the Magpies in January from Marseille before sealing a move to Loftus Road, scored six goals in 14 appearances for the R's last season.
The 26-year-old said: "I'm very happy to be a Newcastle player. It will be a huge honour to play for such a big club. I was very flattered by the club's interest in me back in January and also very happy that they showed interest in me again this summer."
Remy revealed that his international ambitions prompted him to make a switch to Newcastle following QPR's relegation last season.
"The Premier League is the best league in the world and that's where I want to play," Remy said.
"I am very motivated this year to get into the World Cup squad for my country. I know in order to do that I need to have a big season and a successful campaign with Newcastle United.
"I am focused on helping the team achieve success this season and scoring as many goals as I can."
Newcastle's director of football Joe Kinnear, who had only brought in teenager Olivier Kemen from Metz following his appointment by owner Mike Ashley, was pleased to confirm Remy's services for the forthcoming campaign.
"The need for us to strengthen up front was a priority and I have been working very hard to secure one of our targets in this position," Kinnear said.
"I'm delighted to have secured Loic for the season. Now we have him I'm sure he'll be a huge success for us; I know he's hungry for goals and is absolutely committed to helping us achieve success this season."
Magpies boss Alan Pardew hailed Kinnear for landing the player which evaded them earlier in the year.
He said: "Loic is a great player and I'm delighted that Joe has got him on board for us.
"He'll be a great addition to the squad, he gives us strength and pace up front and I'm sure he'll bring plenty of goals.
"It's a big season for Loic, like it is for all our international players ahead of the World Cup, which will only provide extra incentive for him to play at the very top of his game."
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