J Balvin Throws Surprise Party For Girlfriend Valentina Ferrer's 30th Birthday

J Balvin knows how to have a good time ... and he made sure his model GF was doin' the same for her birthday, which is why he threw her a luxurious surprise party!

The Colombian artist rented out a massive villa -- over 7,000 square feet -- on the Miami Beach waterfront for his boo, Valentina Ferrer's, 30th bday Sunday night ... with about 35 people showing up to celebrate, including her family.

We're told he flew her parents, siblings and other family members out from Argentina for the big day -- their 2-year-old son, Rio, was also in attendance but likely didn't party as hard as the rest of them.

The food was another highlight ... J Balvin hired a private chef from Colombia who put together a spread of Argentinian meats to enjoy. There was also a DJ bumping beats throughout the night  -- and no, JB unfortunately took the night off and didn't perform.

We're told Valentina had no idea about the party, so it was a well-kept secret ... especially getting her whole fam to show up!

FYI, it was a whirlwind weekend for the couple ... they were enjoying the NASCAR Cup Series in Tennessee Saturday where J launched his shoe collab with Nike Jordan before jetting over to Miami.