The 33-year-old has signed a two-year deal at Cardiff City Stadium after being released by League Two Portsmouth earlier this summer.
Murphy joins subject to international clearance and offers competition to goalkeepers Ben Amos and Ben Wilson after David Marshall's move to Hull.
"I'm delighted to be here and looking forward to getting going now," he said.
"I'm used to working hard and that's what I'll do.
"Hopefully we'll push each other every day and when it comes to Saturday, you get what you deserve."
Cardiff City have signed former Manchester City and Swansea goalkeeper Brian Murphy on a free transfer.