Farrow, who is a publicist for celebrities including Ozzy Osbourne, Jimmy Carr and Michael McIntyre, issued a statement that reads: "After some serious thought, and with a heavy heart, I can no longer continue my professional duties as Elton John’s personal PR.
"Contractual, media, and PR directional differences between Elton’s new management and myself have proved wider than I ever imagined and leave me with little option but to leave.
"It simply remains for me to thank Elton for all the memorable experiences we have shared."
Farrow set up The Corporation in 2005 and is among the most high profile PRs in the entertainment industry. Click here to read his entry in the 2016 UK Power Book.
Murray Chalmers PR will now handle publicity for the Rocket Entertainment Group - a music management company co-founded by Elton John, which manages his own PR as well as other artists such as Ed Sheeran and Empire of the Sun.
Murray Chalmers said: "I'm really happy with the development of the company and with the new additions to our client roster. Working with Rocket Entertainment Group and Elton John is a big personal thrill for me, and confirms my view that we have one of the best artist rosters in the business. Onwards!"
MCPR's current clients include Coldplay, Kate Bush and The Stone Roses.
This story has been updated with additional information.