Mickey Rourke is finally back to work ... returning to the big screen after his recent eviction and financial struggles -- and he looks locked in and ready to roll.

Check out the pic ... Rourke is getting full hair and makeup done, eyes closed and focused, as he gears up for his acting return.

Rourke's rep Kimberly Hines tells TMZ ... the actor is currently in Utah shooting “Sol Hershowitz’s Guide to Extraterrestrial Life,” where he's taking on a major role in the project. We're told he's one of the film's leads ... playing a paranoid, ex-military conspiracist who claims to have stolen alien technology from the government.

Hines -- who’s also an executive producer on the film -- tells us she’s thrilled to have him back on set, with production now underway.

As you know … Rourke’s been dealing with some tough times, including being evicted from his L.A. home -- which he said was infested with rodents -- and turning down more than $100K raised through a GoFundMe campaign.

He seems to be leaving all that in the past ... getting himself back in the game.