"My decision was not based on my athleticism alone," Rosenthal said as part of his announcement on Twitter. "It was based on me attending the University that I believe can help mold and shape me into a better man and help me reach my full potential on the field.
"... I look forward to changing the narrative and my new journey at UK!"
LSU coach Ed Orgeron raved about Rosenthal's potential before his departure, saying he had the potential to be an NFL first-round draft pick.
Rosenthal struggled to stay on the field, missing spring practice last season and briefly leaving school before returning. He was suspended for part of the season and wound up starting five games.
Kentucky has been active in the transfer market this offseason, bringing in former Penn State quarterback Will Levis, former Ole Miss linebacker Jacquez Jones and former Nebraska wide receiver Wan'Dale Robinson, among others.