The agreement announced this morning ends weeks of speculation and will result in ownership of the title being transferred from the Daily Mail and General Trust (DMGT) to a new company called Evening Standard Ltd for a nominal sum.
Billionaire Lebedev and former President of the Soviet Union Gorbachev already own Russian newspaper Novaya, which DMGT described in a statement this morning as "one of the few pro-democracy newspapers in Russia".
There has been speculation that this is the first move in the Lebedev's bid to establish a media empire in the UK and Western Europe.
Lord Rothermere, chairman of DMGT, said: "We are very proud to have owned the Evening Standard.
"I believe that Alexander Lebedev shares my commitment to newspapers and will continue to invest in the Evening Standard."
He added that DMGT remained "fully committed to journalism and newspaper ownership".
The paper will continue to be printed by Associated Newspapers "for an initial period" with the opportunity to extend these arrangements by agreement.
Ex-KGB spy buys Evening Standard from DMGT
An agreement has been reached to sell London's <i>Evening Standard</i> to a Russian consortium that includes Mikhail Gorbachev and ex-KGB man Alexander Lebedev.