The left back, who captained the Bees last season, made the move across west London to Loftus Road on July 1.
He had spent the best part of five seasons at Griffin Park and helped them from a mid-table position in League One to the top half of the Championship.
Bidwell said: “I want to say thanks to the club for my time there. I know people aren't going to be happy with the choice I've made but I've made the choice now.
“It was the best footballing choice for me. I had four, five good years there. I thank them for their support over that time.
“I don't expect them to be happy with the move but I like to think I helped the club progress when I was there.”
Bidwell's move was met with outcry on social media and, while he insists he hasn't seen it, he is not surprised at the response.
He added: “I haven't seen any of it to be honest – I'm not on social media. I can imagine that comes with the move – it's to be expected.
“When I decided the time was right for me to move on and assessing my options and just because QPR is down the road I wasn't going to turn it down.
“I understand the fans are going to be unhappy. I can come away saying I never gave anything less than 100 per cent.
“Nobody can begrudge me of that. I assessed my options and QPR was the best option for me – that's all it came down to at the end.”
When it came to picking his highlight from his time with Brentford, he went for the promotion season and the following Championship play-off campaign.
He said: “The promotion season and getting into the play-offs. You see the lads that have gone on in the likes of Andre Gray, Alex Pritchard who will get his form going again this season.
“To play with those players, you realise once the season is over how good they were.”