The big-haired guitarist is working with the 'Gangnam Style' singer on a remix of a song wrote with collaborator Kerry Ellis after hearing he was heavily influenced by his old band.
Brian told The Sun newspaper: ''It turns out he's a massive Queen fan and he says he's in the [music] business because of us, which is always nice to hear.''
The rock legend added he was anxious to meet the 35-year-old Korean rapper because of his success with 'Gangnam Style', the most watched music video in YouTube's history.
Brian added: ''I was quite nervous to meet him. The guy's had 1.6 billion views on YouTube. It turns out that he was pretty nervous too. So we just sat there and looked at each other for a while.
''Then we had a good conversation and it was nice. It was a friendly lunch.''
Psy used to listen to Queen - which saw Brian joined by iconic vocalist Freddie Mercury, bass player John Deacon and drummer Roger Taylor - as a teenager and credits them as one of the main reasons he went into the music business.
He said: ''If it wasn't for Queen at Wembley, I wouldn't be a pop star.
''When I was growing up I would watch Freddie Mercury with all those fans in the palm of his hand. He is the best.''