Mel Gibson Expecting 9th Kid!

Mel Gibson's having a baby ... for the 9th time ... with his 26-year-old girlfriend.

Mel and Rosalind Ross, his GF of 2 years, are expecting the newborn sometime early next year ... according to Mel's reps.

60-year-old Mel is an old pro -- he had 7 kids with his ex-wife, Robin, and one more with Oksana Grigorieva. This will be Rosalind's first baby.

People first reported the pregnancy.

Couple fun numbers: 36 and 6 ... the ages of Mel's oldest and youngest kids, as of today.