The 29-year-old, who has established himself as one of the world’s leading tight-heads, is the first signing of the John Mulvihill era and a major boost to Wales’ Capital Region.
Arhip will arrive at the Arms Park following five seasons at the Ospreys, where he has made 91 appearances and developed into one of the hottest prop properties in Europe.
He said: “I’m really excited to be joining Cardiff Blues at a really positive time for the region and I’m looking forward to the challenge that lies ahead.
“I have been very impressed with the progress made at the Arms Park in the last couple of seasons, culminating in winning the Challenge Cup.
“It is a really exciting squad with so much young talent coming through and I am looking forward to adding my experience and competing with the other props.
“The conversations I’ve had with John Mulvihill have been really good and I’m excited about the vision he has set out. I also have a good relationship with new forwards coach Tom Smith, who also joins from the Ospreys.”
Bolstering the strength and depth of the front-five has been the main priority for Mulvihill ahead of a return to the European Champions Cup rugby next season.
He is delighted to bring the destructive scrummager on board as the first signing of the summer and believes it a major signal of intent.
Mulvihill said: “We are all thrilled to have signed Dmitri. He has proven himself a world-class tight-head prop both in terms of scrummaging and around the pitch and is the perfect fit for us as we look to strengthen our pack.
“We need to add quality and depth to our squad to compete in both the Guinness PRO14 and the Champions Cup and this is a great start to our recruitment.
“We remain committed to developing Welsh talent from within but you also need to strike the right balance.
“Dmitri will not only bring a wealth of experience for the entire season but he will have a responsibility to pass on his knowledge to the likes of Dillon Lewis and Kieron Assiratti, who have an abundance of potential.
“I am confident we now have real strength in depth and competition in a vitally important position.”
Cardiff Blues’ recruitment continues apace with Mulvihill and chief executive Richard Holland in advance talks with several other quality players.
And Holland is determined to build upon an impressive 2017-18 season, which saw the Blues secure a return to the top tier of European rugby and lift the Challenge Cup.
He added: “As soon as we became aware that Dmitri could become available, we knew he would be an ideal addition to our front-row.
“It is obviously a great signal of intent and John deserves credit for really selling his vision at Cardiff Blues to Dmitri in the early stages of dialogue with us.
“We are working very hard behind the scenes and were delighted to to retain virtually the entire squad, which gives us real stability.
“But it is also important that the success of last season is just the beginning of the journey and we hope to complete further signings very soon.”