"The Duke asked me about Cilla's funeral - he knew I had been - and I told him all about how funny Paul O'Grady was and how the Bishop of Liverpool had told him to say three Hail Marys before he went to bed, which made the Duke laugh," said Mr Lythgoe after receiving his honour from the Prince on Thursday.
"When the Prince bought her up I thought to myself 'Cilla would have been proud' but of course she was herself an OBE."
Cilla Black died at her Spanish villa on August 1 and her funeral, held in Liverpool nearly three weeks later, was attended by close friend Cliff Richard, who gave the eulogy and a string of celebrities from the British television industry.
Mr Lythgo, 65, originally from the Wirral, made his name in the UK as a judge on Popstars over a decade ago before moving to Los Angeles, where he produced the hit series American Idol before moving back in front of the camera as a judge on So You Think You Can Dance.
He said: "It feels fantastic, I'm very very proud. Everyone is joking in America about it saying 'does OBE stand for Old British Entertainer'.
"It's nice to be back, though - I miss the food! People always knock it but in LA it's only salads that don't taste of anything. Here I just had a pork sausage in batter and I loved it."
Another entertainment industry figure receiving an OBE was Stevie Wonder's manager Keith Harris.
He said: "I was relieved to get through the ceremony without making any major mistakes, to be honest. I was afraid I might do something like trip up and headbutt the Prince."
He added: "The Prince said he was a fan of Stevie Wonder's music. I've worked with Stevie for around 38 years, he is a great guy. But because we've known each other so long its hard for me to react to people seeing him as 'the Stevie Wonder'."
When asked what Wonder thought of his getting the award, Harris said: "He doesn't know yet actually, I thought I'd tell him afterwards. I sent him a text but I didn't bother to make sure he received it so I'm not sure he knows."
