A one-of-one Mike Trout rookie card just sold for OVER $1 MILLION in a private sale to one of the industries top DJ's ... TMZ Sports has learned.

The 2011 "Platinum" Mike Trout Topps Update card is one of the most coveted modern-day baseball cards in existence.

We're told that DJ Skee -- who's worked with top artists like Kendrick Lamar and Post Malone -- along with Mint 10 business partners Courtney and Carter Reum (Paris Hilton's fiancé) ... dropped nearly $1.1 milli on the cardboard.