The 28-year-old has amassed 169 caps for the Blues since debuting for them in 2010, and has since gone on to star internationally for Wales, playing a key role in their recent Six Nations victories over France, Italy and England.
With 14 test caps to his name, Navidi needed to stay in Wales order to remain eligible for the national side as he does not have the 60 caps required to be picked while playing for a foreign club.
“It’s nice to get another contract signed,” he said in a statement on the club’s website.
“Everything is going well here and looking positive for the future, so I was more than happy to sign on the dotted line.
“This new contract takes me beyond 10 years at Cardiff Blues. This place has been massive for me and got me to where I wanted in my career.
“We’ve had some tough times and have had to dig in at but after seeing the boys lift the Challenge Cup in 2009 and to then play a part and lifting it last year was brilliant.
“With the World Cup around the corner it was important to stay in Wales to ensure I’m eligible but I’m also very happy here and hopefully we can achieve like last year and keep pushing forward in the Pro14.”
Cardiff head coach John Mulvihill said he was delighted to retain Navidi.
“Josh is an awesome player and has been a legend for Cardiff Blues, so it is great to retain his services.”
Cardiff currently sit in third-place in their conference in the Pro14 as they prepare to host the Southern Kings at Cardiff Arms Park this weekend.
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