Previously, Borst was an executive officer at Argo Group, where he held roles establishing and leading the US specialty programs business.
He has also held senior roles at OneBeacon Insurance Group and began his career at Travelers Insurance Company.
As Borst takes on the new position, Dan Shea, who has led the Convelo business for the last two years, will move into the newly established EVP and chief marketing officer role.
The senior line-up at Convelo will now include Borst, Shea and Eric Smith, EVP and managing director of underwriting.
Josh Lamberg, founder of Signers National, said: "I’m very excited to welcome Andy to work with Dan and Eric to push Convelo forward to its next phase.”
