Other staff administered CPR to the man who was said to be in cardiac arrest after being injured.
Ambulance staff were called to the scene and were unable to save the man, who was confirmed dead a short time later.
JLR said it was "deeply saddened" and had started an investigation into the circumstances surrounding his death.
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It is not yet clear what injuries the man suffered or how he was hurt.
West Midlands Ambulance Service was called to the plant in Lode Lane just before 15:00 BST on Sunday.
A spokeswoman said paramedics arrived to find "staff administering CPR to a man who had been injured and was in cardiac arrest".
"Ambulance staff and the medics took over advanced life support but sadly, despite the best efforts of everyone on scene, nothing could be done to save the man and he was confirmed dead a short time later."
A JLR spokesperson said: "We are deeply saddened about the death of one of our colleagues and our thoughts are with the individual's family and friends at this difficult time.
"An investigation has been launched into the circumstances surrounding this incident and we are of course co-operating fully with the authorities involved."
A Jaguar Land Rover (JLR) employee has died at the car manufacturer's factory in Solihull.