The Accra-born player began his footballing life at Ken Harrison Babies Colts FC before he made the move to Europe in 1998 to join Bordeaux's youth academy set up. Only a year was spent in France though as he soon moved to Club Brugge in Belgium as a 16-year old where he spent five years before his next home in 2004 was Sporting West Ingelmunster-Harelbeke in the Belgian provincial divisions.
Addo then got a transfer out of the non-league system in 2006 when he joined K.M.S.K. Deinze in the Belgian second division. Only a season was spent with Deinze though before he moved on again, Ransford staying in the same division though as he joined Royal Antwerp, who were then being coached, in their link-up with the Red Devils, by current Manchester United joint reserve team manager Warren Joyce.
Joyce, who has been involved in Carlisle taking James Chester and Oliver Norwood on loan this season, recommended Addo to then Crewe boss Steve Holland in the summer of 2008. The Ghanian though failing to earn a loan deal at Gresty Road in his extended trial spell in Cheshire as he went back to Belgium in late August of that year.
After three years at Royal Antwerp the 27-year old had made 124 appearances for the "Great Old", where he picked up 14 bookings, one red card and scored one goal. He was let go by the Belgian side in the summer though and he now finds himself on trial with Carlisle as he looks to earn a permanent deal with the Cumbrians.