Michael Lohan's Baby Mama -- He's Finally Paying Love Child Support

Michael Lohan's no deadbeat dad -- so says the mother of his 17-year-old love child ... despite court docs proclaiming Michael is more than $300,000 behind on child support.

Kristi Horn -- mother of 17-year-old Ashley Horn -- tells TMZ, she and Michael came to a private settlement out of court regarding the outstanding child support balance ... and Michael has promised to pay up ASAP.

Which is interesting ... because court docs were just filed in Florida, where Michael lives, to enforce a child support judgment Kristi obtained back in 2009 ... ordering Michael to pay $316,720 in unpaid support.

Kristi says she had no part in filing the documents -- they were filed as a matter of course because the order is still active -- but tells us, she's waiting to have the order vacated until after MiLo's fiancée Kate Major gives birth later this month. It's unclear how much Michael agreed to pay her.

Kristi said she and Michael are on great terms.

TMZ broke the story in November ... a DNA test revealed Michael fathered Kristi's daughter Ashley back in the 90s when he was on a break from Dina.

Now ... let's all relive the moment Michael found out he's the father. His face is priceless.