The 31-year-old striker ended speculation linking him with a move away from Fulham by joining the club's west London rivals on deadline day.
QPR have confirmed Zamora has signed a two-and-a-half-year deal for a fee Press Association Sport understands to be worth £6million-plus.
"The ambition of the club was certainly a drawing factor as well [as reuniting with former Fulham manager Mark Hughes]," he told the club's official website.
"I've been lucky enough to speak to Tony [Fernandes, QPR's chairman] and Phil [Beard, QPR's chief executive] has relayed a lot of messages about where this club want to go.
"For me, it was quite an easy decision to be a part of this. The sky's the limit. We're looking to go forward and to grow and I want to be a part of that."
Zamora has cost an initial £4.5million, which will rise depending on performance and will wear the number 52 shirt at the Hoops.
"QPR are certainly a club that are looking to go forward," he added. "That's something that I'm looking forward to being a part of.
"I got on really well with the manager at Fulham. We all grew to like Mark. I think that will be the case here. He's looking to take the club forward.
"I think this was the right time for me to have a fresh challenge. I had some great experiences at Fulham. Going to a European final is special. But this is a new challenge for myself and I'm thoroughly looking forward to it."
Zamora is not eligible to feature against Aston Villa on Wednesday night but fellow new boy Djibril Cisse could make his debut, subject to international clearance being received at least one hour before kick-off.
The 30-year-old former Liverpool and Sunderland player returns to England after a spell at Lazio for a fee in the region of 5million euros (£4.18million).
"QPR have a hugely ambitious project," Cisse said. "When I talked to the manager, he spoke highly of the club and where he wants to take it over the next few years.
"He wanted to sign me at Manchester City and now I am finally here with him at QPR.
"He wants to achieve big things here - that was all I needed to hear from him."
As well as signing Zamora and Cisse, QPR also let some fringe players move on.
Bradley Orr joined Blackburn on a two-and-a-half-year deal, while fellow defender Matthew Connolly will spend the rest of the season on loan at Reading.
Martin Rowlands and Petter Vaagan Moen both had their contracts terminated by mutual consent.