Larry Johnson's first baby mama is coming to the ex-NBA star's defense -- telling TMZ Sports he's NOT a deadbeat dad ... claiming he doesn't owe her a dime.
We broke the story ... Johnson -- who made more than $80 million in his NBA career -- filed for bankruptcy and in official docs he listed 4 of his baby mamas as creditors, stemming from back child support payments.
But Dronda Gillam -- who has a 22-year-old son with L.J. -- says there must've been a mistake ... because she NEVER went after Larry for child support ... ever.
"We have a great relationship. I've never had a problem with him over money," Gillam says.
"He’s always been supportive. We never had anything set up through the court system because we didn't need that."
She adds, "He's a really great guy. He just fell on tough times."
We reached out to Johnson and his people for comment -- so far, no word back.