Berghan left Warriors at the end of the season after two years at Scotstoun.
Posting on his Instagram page, Berghan said: "I have made the decision to call time on my rugby career.
"Since coming over to Scotland back in 2014 I have achieved more than I could have ever imagined. I feel very fortunate to have played rugby for a living and will be forever grateful to everyone who has played a role in making that happen - from my junior coaches to the supporters and fans throughout the years, without you, I truly wouldn't be where I am today.
"To all my teammates over the years, thank you for making my time in sport what it was, especially off the pitch! I have made friends for life.
"I am really excited to have the opportunity to move into the corporate world with BlackRock and will attack the new challenge with the same commitment that I did in my rugby career."