The under-performing centre forward has been a disappointment in his second spell at Wanderers, and once his best mate Dougie Freedman left it was always likely that Mason would find himself out of favour.
Cardiff manager Russell Slade said:
"We have eight players out on loan and we are keeping up-to-date on how they are doing,"
"I am, in particular, keen to see how Joe Mason is going at Bolton."
Well I'll fill you in Russell - despite scoring a hattrick against Rotherham United, he's been crap.
It is believed that the season-long loan deal does contain a recall clause should Cardiff choose to bring the striker back to Wales in order to boost their efforts for the rest of the season.