"Empire" star Jussie Smollett is keeping it as real as his TV mama Cookie does ... saying he's NOT hookin' up with Michael Sam ... despite the fact they've been spending A LOT of time together recently.
Just last week, Sam posted 3 PICS with Smollett on social media ... leading some people to believe they were more than just friends.

But when we saw Jamal Lyon working out in L.A. on Monday, dude wanted to set the record ... er, straight -- they're close, but ain't nobody humpin' around (shout-out to Bobby Brown).
BONUS -- Smollett also responded to 50 Cent, who's been BLASTING "Empire" over social media ... but surprisingly, he didn't fire off a Lucious Lyon style retaliation. Instead, he's killing with kindness.