The 20-year-old central defender makes the switch to the Furness Building Society Stadium after appearances in both Premier League 2 and the EFL Trophy so far this term.
He has risen through the ranks at the Saints, starting in their under-18 side, before progressing to the under-21’s and finally their under-23 side who play in Premier League 2.
Cook signed a professional contract with them in the 2015/16 season and joins up with the Bluebirds squad ahead of their game at Torquay United on Saturday.