Jimmy left Yellowstone because he was seriously injured during a rodeo accident and, with John Dutton's blessing, he decided to leave the Montana ranch to pursue his dream of being a rodeo cowboy at the 6666 Ranch in Texas. John allowed Jimmy to leave with his fiancée Emily, as a way of supporting Jimmy's growth and a new chapter in his life. This departure happened in season 4, with John releasing Jimmy from his obligation to stay at Yellowstone, recognizing his maturity and trusting that Jimmy would remain loyal to the Yellowstone family even from afar. The move was also likely tied to the planned spin-off show centered on the 6666 Ranch, where Jimmy is expected to feature prominently. Jimmy had been branded with the Yellowstone logo, symbolizing a lifelong bond to the Yellowstone Ranch, but John explicitly gave him permission to break that bond and move on.