The giant forward, who stands 6ft 6in and weighs 18st 6lbs, has played for Wales Under-19s, Wales Under-21s, Wales Universities and the Barbarians.
Man-mountain Dicomidis, who also represented Cyprus in 2011, has been an almost ever present in the Pontypridd set-up over the last decade and was named club captain in 2010.
"I'm excited about the opportunity to become part of the Blues squad and taking my chance at professional rugby," said Dicomidis.
"You always hope you'll get the call to join a full-time set-up and I've spoken to Dale (McIntosh) about the region and what is expected. I'm determined to grasp this opportunity with both hands and show what I can achieve.
"I've had an incredible time at Pontypridd, have made so many friends and leave with so many fond memories. I'd like to thank them for their understanding and wish them every success for the rest of this season. I also need to thank my employer MPCT for their support and backing.
"I join up with Blues next week and can't wait to get started in a new environment and really push myself to show what I am capable of."
Director of Rugby Phil Davies said: "We're really pleased that Chris will join the region. He is a fine player who has played extremely well for Pontypridd over the last decade.
"Chris is someone I know very well and also Chief (Dale McIntosh) has a very close relationship with him from their time together at Ponty.
"He will strengthen our second row resources, with Lou Reed and Bradley Davies currently sidelined, and I know he is determined to take this opportunity. We are excited to see what he can achieve in a full-time professional environment."