Best previously held the role at the province, for whom he has made 152 appearances, between 2007 and 2011.
And he insists the experience he's picked up in the last three years will make him a better captain than ever before.
"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," he told the club's website.
"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."