The 31-year-old has also captained Ireland on four occasions and led out the British & Irish Lions against the Brumbies in the 2013 tour to Australia.
Commenting on the Ulster captaincy, Best said: "It is a huge honour to captain your province. I enjoyed doing it a few years ago but in 2011, I felt I just needed to step down and to concentrate on my game.
"It is nice to have been asked to do it again. With the extra experience that I have gained at provincial and international level in recent years I believe that I am more equipped than ever before to lead this group of players.
"Being the captain of Ulster is something that I absolutely love doing and I am looking forward to the challenge of the new season."