According to the Clark County Office of the Coroner/Medical Examiner in Nevada ... the official cause of death for Rose was determined as hypertensive and atherosclerotic cardiovascular disease.

Rose had also been battling diabetes mellitus, officials added.

His death was ruled a natural one.

TMZ Sports broke the story ... Rose was found dead by a family member in his Las Vegas home on Monday afternoon.

He had just been seen on Sunday at a Fiterman Sports Group meet-and-greet in Nashville ... and while he was in a wheelchair because his back had been bothering him, we're told he appeared to be in good spirits.

He even posed for a picture during the event with some of his famed Big Red Machine teammates ... and you can see, he had a big smile on his face.

Rose spent almost all of his legendary career with the Cincinnati Reds ... but he did log at-bats for the Phillies and Expos too.

Of course, in retirement from his playing days, he was banned from baseball by MLB commissioner Bart Giamatti -- after league officials determined he had placed wagers on the sport.

Rose initially denied the claims for years, but fessed up to it all in the mid-2000s.

The league said following his death on Monday it "extends its deepest condolences to Pete Rose's family, his friends across the game, and the fans of his hometown of Cincinnati, Philadelphia, Montreal and beyond who admired his greatness, grit and determination on the field of play."

Pete was 83 years old.