The paper will make the change on Monday October 12, more than doubling its circulation from its current level of around 250,000 copies.
Andrew Mullins, managing director of the London Evening Standard, said: "Sustaining a paid-for afternoon newspaper had its challenges even before the freesheets were launched in 2006 ... Being a quality newspaper with large scale and reach should transform our commercial fortunes."
Details about how the Standard will be distributed and what will happen to the current vendors have not yet been released.
The Standard's Russian owner Alexander Lebedev said his intention to make the paper available to a wider audience was for it to function as a "deterrent against corruption".
"I want to invest in newspapers in general for this purpose and the London Evening Standard in particular."
Lebedev believes that other quality papers will end up following his lead.
Geordie Greig, editor, was keen to underline the Standard's commitment to remaining a quality newspaper.
Greig said: "This is an historic moment and great opportunity for the London Evening Standard. Its owners will be funding the distribution of over 600k copies of the newspaper, making it available to more Londoners than ever before. And most importantly this will be a quality newspaper.
"The Standard has an exciting and secure future with this new, pioneering strategy of more than doubling our distribution. We will remain the only London newspaper committed to a tradition of high quality journalism with the finest writers and undiminished commitment to the best reporting of news, business and sport."
In the middle of May the Standard underwent a high-profile relaunch. The month saw its circulation drop 20% from April to 210,901, but in June it recovered 12% to reach 236,075.
In July the Standard changed its ABC reporting regime to become a regional title.
The move will raise fresh speculation about the future of afternoon free newspaper London Lite, owned by Associated Newspapers, the former owner of and still a 25% shareholder in the Evening Standard. Much of the Lite's editorial is supplied by the Standard.
Speculation about the future of the Lite has been rife since its main competitor, News International-owned thelondonpaper, was closed by News International at the end of last month.
Associated was not commenting publicly on the developments but it is understood it is taking Standard's move as another factor to consider in a review of the Lite that has been underway since thelondonpaper closed.