Jon Jones spent his entire career in the light heavyweight division, but, not anymore ... the UFC legend is now a heavyweight, and we're seeing JJ's physique for the first time!
35-year-old Jones posed for promotional photos on March 1 ahead of his UFC 285 fight with 32-year-old former interim champ Ciryl Gane ... and you can clearly see 6'4" Jon packed on some serious size.
Jones systematically bulked up, adding muscle over the last 2+ years.