The versatile player has established himself as a firm favourite during his 10 seasons to date at Wales' Capital Region, amassing 169 appearances, in which he has scored 21 tries.
He has been crowned Cardiff Blues Player of the Season on several occasions and has now transferred his imperious regional form to the international stage.
Following a four-year hiatus between his first and second caps, Navidi burst back into the Test arena in 2017 and has now racked up 14 appearances, starting every Six Nations game this year.
He was delighted to put pen to paper to remain at Cardiff Blues and has high hopes for the future at the Arms Park.
Navidi said: "It's nice to get another contract signed. 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 Amlin 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."
The Blues are currently in the top three of Conference A in the PRO14, which warrants not only a play-off spot but qualification for the Champions Cup.
Head coach John Mulvihill has been delighted to see Navidi equip himself so well in the Six Nations and insists he will be vitally important not only in this season's play-off race but the future success of Cardiff Blues.
Mulvihill said: "Josh is an awesome player and has been a legend for Cardiff Blues, so it is great to retain his services.
"He has shown over the past few months how important he is not only to Cardiff Blues, but the national squad and you can see that in the Six Nations.
"His energy, work-rate, physical presence is so important to us. He is a great team man, super professional, on and off the field, and is someone who constantly pushes his limits and boundaries to be the best possible player he can be.
"We're looking forward to welcoming him back following a successful Six Nations to bolster our back-row as we enter a crucial final block to the season."