Kadyrov won 81.1% of the vote casts in Sunday's poll, according to the RIA Novosti news agency.
Chechnya's estimated 560,000 registered voters had a choice of seven candidates, but two of Kadyrov's main rivals withdrew during the campaign and a third, Malik Saidullayev, a wealthy businessman and former prime minister, was disqualified because of alleged irregularities.
The election has been widely criticised by critics as well as the Chechen independence fighters.
Leader of the Chechen fighters, Aslan Maskhadov vowed to "rid our country of the occupiers and put an end to relations between Russia and the Chechen state, no matter how difficult the task".
Elected in 1997 in an internationally recognised poll, Maskhadov was barred from running in the ballot, although he had said he had no intention of taking part in what he considered a sham.
Russian media divided
Russian media were divided in their assessment of the poll, some critical and others welcoming the election of a new Chechen authority.
Nezavisimaya Gazeta and the business daily Kommersant both stressed the lack of genuine opposition to Kadyrov, while the liberal Gazeta pointed to the resemblance to Soviet-era elections "with their turnouts of 99.998 percent."
But Izvestia said that "even if the new authority is imperfect, it will still be legitimate."
The election took place amid a
high security presence
However, critics have warned that the poll, widely seen as skewed in favour of Kadyrov, would do little or nothing to bring an end to the fighting.
Critics have also contested the poll’s legitimacy on the grounds that it took place in the midst of a war.
The election, which took place amid a high security presence, came almost exactly four years after 80,000 Russian troops poured into the Caucasus republic in what Moscow called an "anti-terror operation" to crush a separatist insurgency.
The conflict has since turned into a brutal guerrilla war of attrition that has caused tens of thousands of civilian lives with Russian soldiers accused of grave human rights abuses.
The pan-European rights body OSCE refused to send observers to the poll, and the rapporteur for Chechnya of the Council of Europe's Parliamentary Assembly, Andreas Gross, said he could not send observers to what was "not a real election."
The Organisation of the Islamic Conference (OIC) and the Arab League were the only international organisations to send observers.