Sean has signed a deal that will see him with the Warriors until the end of May 2015.
Perth-born Sean joined Glasgow from Rotherham in 2003 after making a name for himself in the Scotland Sevens team and soon became a huge favourite with the Hughenden faithful.
He quickly caught the eye of the Scotland selectors and has gone on to win 60 caps and has played in two World Cups.
His other representative honours include Leicestershire Colts (while he was at Sheffield Hallam University) and Scottish Exiles. He joined Rotherham in 2000 and skippered their U21 team.
After two impressive seasons with Glasgow he moved to Northampton Saints in 2005 and then Scarlets in 2009.