Conor McGregor is gonna be working in Vegas during UFC 200 weekend -- just not in the Octagon.

Instead, he'll be hosting a post-fight party at a massive nightclub at the Wynn Hotel ... TMZ Sports has learned.

McGregor has signed on to host an "action packed evening" at Intrigue nightclub -- with special guest DJ Konflikt.

Of course, McGregor was supposed to be FIGHTING that weekend and making $10 MILLION. Instead, he'll be slamming whiskey for a lot less.