On Monday morning Goldman announced that Mr Schwartz would leave the bank after a 20-year career, mostly in the securities division.
The question of Blankfein's successor has been a topic of debate across the financial industry since Friday, when the Wall Street Journal reported that the CEO would step down as early as the end of this year.
Before taking the co-COO role, Solomon had been a cohead of investment banking in NY for a decade.
Harvey Schwartz's resignation comes after 20 years with Goldman Sachs.
Goldman made no mention of Blankfein's future plans in its announcement.
Vertical Group analyst Dick Bove, who sharply criticized Blankfein's leadership of Goldman, said selecting Solomon would position the bank for new opportunities amid changing United States policies on taxes, trade and potentially fiscal stimulus.
The end of Blankfein's tenure at the top of Goldman Sachs has always been a Wall Street talking point.
Mayo predicted that the CEO transition would happen next year, during Goldman Sachs' 150th anniversary as a firm, when he said the firm should be better positioned for Blankfein to exit on top. What's more, Blankfein and JPMorgan's Jamie Dimon are the only two remaining big bank CEOs from the 2008 financial crisis.
"I look forward to continuing to work closely with David in building our franchise around the world, serving our expanding client base and delivering strong returns for our shareholders, "Blankfein said in the statement".
Shares of Goldman Sachs finished up 1.0 percent to $273.38.
By contrast, Solomon has an investment banking background.
Schwartz's departure leaves Solomon - who has gained notoriety in recent years for moonlighting as a DJ at nightclubs in NY and Miami - as the apparent successor to Blankfein. In 2009, Schwartz' department made more than $33 billion for the bank. He has also taken on a leading role in the firm's diversity push and initiatives to improve working conditions for young bankers.