Under the sanctions, published on Friday in the EU's official journal, Rosneft, Transneft and Gazprom Neft will be prevented from raising long-term debt on European capital markets.
There are also travel bans and asset freezes against leading members of Vladimir Putin's inner circle, including the businessman Sergei Chemezov, chairman of defence and industrial group Rostec and a close associate of Putin from his KGB days in East Germany.
Others targeted are Igor Lebedev, deputy speaker of the Russian lower house of parliament, and Vladimir Zhirinovsky, an outspoken nationalist politician, as well as a number of leaders of pro-Russia separatists in eastern Ukraine.
The US is understood to be planning to limit access to Russian banks, including Sberbank, later on Friday as part of a concerted western effort to penalise what it sees as Russian attempts to destablise Ukraine by backing pro-Russia separatists with troops and weapons.
Last week, Russia and Ukraine agreed to a ceasefire that remains in place despite repeated violations. As part of the agreement, on Friday the Ukrainian government and rebel forces exchanged dozens of prisoners captured during fighting.
The transfer took place in early hours outside the main rebel stronghold of Donetsk under the watch of international observers. Ukraine's president, Petro Poroshenko, said 36 Ukrainian servicemen were released after negotiations. He said a further 21 soldiers were freed the day before. Ukrainian forces handed over 31 pro-Russia rebels detained over the course of the five-month conflict.
Shortly after the prisoner exchange, a volley of rocket fire was heard from central Donetsk. Hundreds of prisoners are believed to be held by both sides, although no firm figure has been provided by either.
The latest sanctions are designed to keep up pressure on Russia, which denies sending troops into eastern Ukraine and arming the separatists.
In July, the US effectively cut off five Russian financial groups – VTB Bank, Gazprombank, Bank of Moscow VEB and Russian Agriculture Bank – from US equity and debt markets.