That milestone lifts the last legal barrier to his serving as president of the war-ravaged North Caucasus republic.
Kadyrov, a former separatist who maintains close ties with Russian President Vladimir Putin, is the son of former Chechen leader Akhmed-hadji Kadyrov, who was assassinated in May 2004.
The term of current Chechnya President Alu Alkhanov is due to expire in 2008. The Chechen parliament, however, has already taken steps toward amending the constitution to allow for early elections should Alkhanov be incapacitated.
Kadyrov has said he is "not ready" to serve as president, but would consider doing so if it were "the will of the people."
As prime minister, he has been credited with initiating massive reconstruction projects and quelling the separatist movement. But his reputation has been tainted by allegations that his 10,000-strong personal army -- the so-called kadyrovtsy -- is responsible for a wave of murder and kidnappings, often targeting the civilian population.
As part of the celebration today, the main airport in the Chechen capital, Grozny, was reopened in a ceremony aimed at demonstrating "normalization" following more than a decade of fighting.
Also today, Chechen officials opened a new symbolic gate to the city on the road from neighboring Daghestan, featuring two 17-meter towers.
(AP, Interfax, Reuters, AFP)