Gronkowski's house was burglarized on February 5 ... while RG was in Minnesota for the Super Bowl. Gronk's bedroom was locked, so the burglars never entered his room ... however, stuff was taken from the house.

After a 6-week investigation, Foxborough PD announced they arrested a man named Anthony Almeida -- 31 years old.

Almeida was charged with breaking and entering, 2 counts of receiving stolen property, and malicious destruction of property.

Police say they recovered an Apple Watch, a Rolex, and 2 rare coins. They are still looking for multiple firearms that were taken.

But that's not all ... cops are on the hunt for 2 other men they believe also participated in the robbery.

FYI -- Gronk PERSONALLY made the 911 call ... saying "This isn't an emergency ... this is just uh, Rob Gronkowski calling. And while I was gone, my whole house got robbed while on the Super Bowl trip and I just got back."