Mickey Rourke is making sure to act professionally on set ... telling us his hotel room trashing days are behind him.

We caught up with the actor at LAX on Saturday ... and, he told us he's happy to be working again -- and, he's on his best behavior.

Rourke admits he wasn't acting correctly over the last couple decades -- he even says his psychiatrist once told him he didn't know how to take accountability for anything ... something he says he's trying to work on.

The veteran actor also cites a priest who has helped him reflect on his past ... and, he adds he's just so grateful to be in the position he is now.

As for the best movie of his career ... Rourke says he hasn't made it yet -- which is pretty shocking given the dude has Golden Globe on his shelf!

Remember ... Mickey was facing eviction after apparently owing nearly $60K in unpaid rent. He claims he stopped paying rent because of a rodent infestation.

We recently published photos of him back on set of the new movie "Sol Hershowitz’s Guide to Extraterrestrial Life" ... in which he's one of the leads.

As for the plan moving forward ... Rourke says it's simple -- time to kick some ass!!!