Alex Rodriguez: Santa Got Me a New PRIVATE JET!

Christmas came early for A-Rod ... 'cause the ex-MLB superstar just unwrapped his brand new PRIVATE JET -- and it's awesome!

We're told Alex Rodriguez got rid of his old LearJet 60 a while ago ... and decided to upgrade with a Gulfstream IV.

According to people familiar with the planes, Alex's new jet has DOUBLE the flight mileage capacity as the old jet ... which means it's better for international travel.

And get this ... the jet seats up to 14 people -- perfect for Jennifer Lopez and her kids!

The new Gulfstream was delivered to Alex in Florida on Wednesday with his A-Rod Corp. company logo painted on the tail ... just in time for the holidays!