According to TMZ, the musician was found by authorities close to his home with a gunshot wound in the head.
Authorities have reportedly claimed that the shots were self-inflicted and imply that Birch took his own life.
There was no suicide note left, and the involvement of drugs or alcohol were not apparent in the death.
Birch has worked with John since 1992 and has also played with such high profile acts as Billy Joel, Tina Turner, Stevie Wonder, Eric Clapton and more.
He was 56 years old at the time of his death.
Watch Robert Wayne Birch performing with Elton John on The Late Show with David Letterman in 2011 below: