Kylie Jenner's Hairstylist Jesus Guerrero Cause of Death Revealed

Kylie Jenner's hairstylist, Jesus Guerrero, died from severe pneumonia ... TMZ has learned.

According to the Los Angeles County Department of Medical Examiner, Jesus had a weakened immune system and, as a result, contracted pneumonia, as well as Cryptococcus neoformans, a fungal organism. The manner of death is natural.

As we reported, Guerrero arrived at a local hospital on the afternoon of February 21 after complaining of not feeling well. His death was pronounced the following day by a hospital doctor.

A deputy medical examiner completed an examination of Guerrero on March 5 -- and after the return of relevant tests and studies, the cause and manner of death were certified June 2.

We broke the story ... Jesus had lost 20 pounds and was complaining of chills and hot flashes leading up to his unexpected death.

We're told he'd been feeling sick since September 2024, but continued with work commitments in Ireland, England and the United Arab Emirates.

When Jesus got back to the United States from his last overseas trip, he was taken to an L.A. hospital and died the next day.

Jesus' sister described his death as "sudden and unexpected," and a bunch of celebs who worked with Jesus posted emotional tributes ... including Kylie, Katy Perry and Jennifer Lopez.

As we first reported ... Kylie covered the cost of transporting Jesus' body back to his family in Houston, Texas and she announced she would pay for his funeral.

Jesus was 34.