He was also found guilty of three attempted murders.
Nevzlin was once a major shareholder in the Yukos empire, which has since been divided up and sold off by the Russian state to pay for huge back-tax claims levied by the tax authorities.
He was also one of the closest advisers of Mikhail Khodorkovsky, the former head of Yukos.
|Mikhail Khodorkovsky during his trial in Moscow [AP]
Khodorkovsky, who is serving an eight-year jail term for tax evasion and fraud, says he was a victim of corrupt officials under Vladimir Putin, the former Russian president, who wanted to carve up his business empire and who feared his political ambitions.
Russia has asked Israel to extradite Nevzlin, who has repeatedly denied the charges.
Nevzlin said the court was acting out a show trial orchestrated by the Kremlin and he would appeal to the European Court of Human Rights.
In a statement read out by his spokesman, Nevzlin said: "The decision of the court was written in advance by the Kremlin and there is no surprise in this decision.
"This is a show trial managed under the supervision of the Kremlin and controlled by Putin and his gang. I intend to appeal to the European Court of Human Rights against this show trial that was held in Russia."
The Moscow court said Nevzlin worked with Alexei Pichugin, Yukos's former head of security, to kill people who were hindering the interests of the company, which had major stakes in oil, banking and commodity trading.
The judge said Nevzlin and Pichugin, who was sentenced to 24 years in prison in 2006 for carrying out murders, had organised the 1998 murder of Valentina Korneyeva, who owned a building in central Moscow that Menatep, a Yukos holding firm, wanted to buy.
The judge also said Nevzlin ordered the 1998 murder of Vladimir Petukhov, the mayor of the Siberian town of Nefteyugansk, where Yukos's biggest oil production unit was based.
The judge said the murder had cost Yukos $150,000.
Prosecutors said Petukhov, who had fallen out with Yukos and was demanding tax payments to the local budget, was shot dead on June 26, Khodorkovsky's birthday.
Yukos officials said the timing of the murder was intended to discredit Yukos bosses.
The court's decision is the latest chapter in the demise of the Yukos-Menatep empire, which amassed a fortune by buying state assets cheaply and trading commodities in the chaos after the fall of the Soviet Union.
Khodorkovsky, once Russia's richest man, fell foul of the Kremlin in 2003 and was arrested by the FSB security service at an airport in Siberia.
Putin, while still president, repeatedly said Khodorkovsky had committed serious crimes and must pay the penalty.
Prosecutors have recently laid fresh charges against Khodorkovsky, including money laundering and embezzlement.
In his statement, Nevzlin said: "Courts all over the world have ruled that Russia is a place of political persecution - courts in England, in Switzerland, in the Netherlands, in Israel - so the only place such a show trial can be held is in Russia."