McKenzie yesterday picked up the best original song Oscar for his composition Man or Muppet, from The Muppets movie.
His father Peter watched the Academy Awards ceremony with Bret's brothers in their Wellington home.
They had some nervous moments in the lead-up to the award.
"(It was) very frustrating when those guys kept dropping the cymbals (funnymen presenters Will Ferrell and Zach Galifianakis continually dropped the crash cymbals they were playing as they quipped about what a pleasure it was to present the award - "as serious musicians''). I had a very long few seconds waiting for the announcement and then it was very emotionally tear-filling when it was announced, I can assure you.''
McKenzie would take his Oscar back to his Wellington home, and put it "somewhere out of reach of the children I'd say'', Peter told Radio New Zealand this morning.
He hadn't prepared his acceptance speech two days before the ceremony so his father told him he'd better get to it.
"I said `well you've got a 50 percent chance - and I think you've got a 100 percent chance-_ of winning, so you'd better make up your speech. So he [Bret] did that and thought he handled that much better than I was handling mine I can assure you of that,'' Peter said.
In a brief acceptance speech, McKenzie spoke of watching The Muppets on TV as a child in New Zealand: "I never thought I'd get to work with them.''
He added: "I was genuinely star-struck when I got to meet Kermit the Frog, but once you get to know him, he's just a normal frog. And like many of the stars here, he's a lot shorter in real life.''
Peter doubted winning the coveted award would go to his son's head.
"He's a very modest guy, I'm sure he'll just handle it as part of his life. It won't make any difference to him, he'll cruise through it as he's cruised to this degree of success now.''
Peter said the Flight of the Conchords still planned to tour New Zealand and Australia later this year.
Casting agents say McKenzie has blown his Hollywood career wide open and should expect immediate rewards in the industry, say casting agents after the New Zealander claimed the Academy Award.
Asked backstage how a small country produced so many award-winning artists, the Wellington musician and comedic actor said: "It's a great place to grow up. You can do whatever you want there. Whereas in America I think everyone's obsessed with their careers, in New Zealand you get to just live your dreams.''
McKenzie already has a Grammy to his name, but Australian publicity mogul Max Markson said the 36-year-old's star was now brighter than ever.
"The world is definitely his oyster. He's already a fantastic talent ... but for him professionally it's amazing. He'll definitely get more work out of this if he wants it.
"What you've got here is someone who has got a fantastic ability to write a song and he's on the money popularity-wise and he's a young songwriter.''
Winning an Oscar for Disney would make the company keen to hire McKenzie again, Mr Markson said. "They use so much original music and now they'll be over the moon with him ... and so if he wants to do more writing, Disney already know who he is.''
McKenzie broke into Hollywood in the television comedy Flight of the Conchords, the show he wrote and starred in with long-time collaborator Jemaine Clement.
He said, jokingly, that splitting from Clement appeared to have worked in his favour: "It seems to have gone really well.
"But I'm looking forward to writing with Jemaine in the future. Because I'll be able to pull out the Oscar card and say, `We should play this chord ...'''
McKenzie thanked his parents Peter McKenzie and Deirdre Tarrant for "never telling me to get a real job''.
His mother said from LA, where she was babysitting his children Vito and Leo, that the family were "a bit overwhelmed ... we're all in speechless mode''.
"[Bret] rang and all he could say was, `I can't believe it, Mum, I can't believe it.' The city is just madness. Everyone's famous, and then there's Bret. And now he's famous, so it's all good.''
Ms Tarrant said she felt indescribably proud seeing her son collecting the golden statue.
McKenzie also thanked his wife, Hannah Clarke, who was in the audience.
Yesterday's other NZ nominees, Daniel Barrett, R. Christopher White, Joe Letteri and Dan Lemmon from Weta Digital, missed out on the Best Visual Effects Oscar. They were nominated for their work on Rise of the Planet of the Apes.
The French silent movie The Artist and Martin Scorsese's Hugo won five Oscars each, and Meryl Streep ended a 29-year drought to win the best actress award.
- APNZ and The New Zealand Herald
