Jimmy Iovine threw the dopest party ever at his house in L.A. last night -- and here's the thing ... Oprah wasn't the big star there.
A star struck Oprah gushed that she got to meet Mick Jagger for the first time. But it doesn't end there -- other guests included Diddy, Kanye West, Kim Kardashian, Brian Grazer, Dr. Dre and a bunch more.
By the way -- Jimmy wasn't playing a mix tape for background ... R. Kelly gave an impromptu performance ... and we believe Diddy did too.
The way it looks to us -- this was a combo party during Emmy weekend, but also a bash to celebrate the birthday of Liberty Ross .. who he's rumored to be banging.