Less than six months after the collapse of Drexel, the founders of Apollo had already begun a series of ventures. Apollo Investment Fund L.P., the first of their private equity investment funds, was formed to make Investments in distressed companies. Apollo's first fund raised approximately $400 million of investor commitments on the strength of Black's reputation as a prominent lieutenant of Michael Milken and key player in the buyout boom of the 1980s. Lion Advisors was set up to provide investment services to Credit Lyonnais, which was seeking to profit from depressed prices in the high yield market.

Lion Advisors (or Lion Capital), which was founded at the same time as Apollo in 1990, focused on investment management and consulting services to foreign institutional accounts targeting Investments in public and private high yield debt securities in the US. In 1992, Lion entered into a more formal arrangement to manage the $3 billion high-yield portfolio for Credit Lyonnais which together with a consortium of other international Investors provided the capital for Lion's investment activities. The Lion Business would ultimately be replaced by Ares Management.

Also in 1995, Apollo founding partner Craig Cogut left the firm to found a smaller competitor Pegasus Capital Advisors. Since inception Pegasus has raised $1.8 billion in four private equity funds focused on Investments in middle-market companies in financial distress. In 1997, Apollo co-founder Tony Ressler founded Ares Management as the successor to its Lion Advisors Business which would manage collateralized debt obligation vehicles.

Ares Management, founded in 1997, was initially established to manage a $1.2 billion market value collateralized debt obligation vehicle. Ares would grow to manage a family of collateralized loan obligation (CLO) vehicles that would invest in capital markets-based securities including senior bank loans and high-yield and mezzanine debt. Ares was founded by Antony Ressler and John H. Kissick, both partners at Apollo as well as Bennett Rosenthal, who joined the group from the global leveraged Finance group at Merrill Lynch.

In 1998, Apollo raised its fourth private equity fund, Apollo Investment Fund IV, with $3.6 billion of investor commitments. Among the Investments made in Fund IV (invested through 2001) were: Allied Waste Industries, AMC Entertainment, Berlitz International, Clark Retail Enterprises, Corporate Express (Buhrmann), Encompass Services Corporation, National Financial Partners, Pacer International, Rent-A-Center, Resolution Performance Products, Resolution Specialty Materials, Sirius Satellite Radio, SkyTerra Communications, United Rentals and Wyndham Worldwide.

Apollo has been an active private equity investor through the mid-2000s buyout boom. The following is a list of Apollo's most recent and currently active private equity Investments. The bulk of these Investments are held in Apollo Investment Fund V, VI and VII.

Ares I and II which were raised were structured as market value CLOs. Ares III though Ares X were structured as cash flow CLOs. In 2002, Ares completed a spinout from Apollo management. Although technically, the founders of Ares had completed a spinout with the formation of the firm in 1997, they had maintained a close relationship with Apollo over its first five years and operated as the West Coast affiliate of Apollo. Shortly thereafter, Ares completed fundraising for Ares Corporate Opportunities Fund, a special situations investment fund with $750 million of capital under management.

In 2004, Ares debuted a publicly traded Business development company, Ares Capital Corporation (NASDAQ:ARCC). In 2006, Ares raised a $2.1 billion successor special situations fund (Ares Corporate Opportunities Fund II).

The 2005 - 2007 period marked a boom period in private equity with new "largest buyout" records set and surpassed several times in an 18-month window from the beginning of 2006 through the middle of 2007. Apollo was among the most active Investors in leveraged buyout transactions during this period. Although Apollo was involved in a number of notable and large buyouts, the firm largely avoided the very largest transactions of this period. Among Apollo's most notable Investments during this period included Harrah's Entertainment, a leading US Gaming and casino company; Norwegian Cruise Line, the cruise line operator; Claire's Stores, the retailer of costume jewelry; and Realogy, the real estate franchisor that owns Coldwell Banker, Century 21 and Sotheby's International Realty.

AAA was launched in August 2006, shortly after Kohlberg Kravis Roberts completed an initial public offering for its $5 billion for its KKR Private Equity Investors vehicle in May 2006. Apollo raised a total of $2 billion for AAA including the vehicle's $1.5 billion IPO and a subsequent private placement.

In December 2008, Apollo completed fundraising for its latest fund, Apollo Investment Fund VII with approximately $14.7 billion of investor commitments. Apollo had been targeting $15 billion, but had been in fundraising for more than 16 months, with the bulk of the capital raised in 2007.

In December 2009, it was announced that Apollo would acquire Cedar Fair Entertainment Company shares and the company would be become private underneath the management group. The deal includes a cash payment of $635 million and assumed debt which gives the transaction a value of $2.4 billion. It was later announced in April 2010 that the deal was pulled due to poor shareholder response.

In March 2012, Apollo made a second attempt to acquire an amusement park operator with a $225.7 million offer for Great Wolf Resorts. In November 2012, Apollo acquired The McGraw-Hill Companies' education division ("McGraw-Hill Education") in a deal totaling $2.5 billion.

Apollo is operated by its managing partners, Leon Black, Joshua Harris and Marc Rowan and a team of more than 250 investment professionals, as of March 31, 2013. The firm's headquarters are located in the Solow Building at 9 West 57th Street in New York City, and the firm operates additional offices in Purchase, New York, Los Angeles, Houston, London, Frankfurt, Luxembourg, Singapore, Hong Kong and Mumbai

Apollo has historically relied primarily on private equity funds, pools of committed capital from pension funds, insurance companies, endowments, fund of funds, high-net-worth individuals, family offices, sovereign wealth funds and other institutional Investors. Since 2014, Apollo has begun investing its eighth private equity fund, Apollo Investment Fund VIII, which raised approximately $18 billion of investor commitments. In 2017, Apollo raised $24.6 billion for its ninth flagship private equity fund, making it the largest in history. Since inception in 1990, Apollo has raised a total of nine private equity funds, including:

In June 2015, Apollo Global Management made a successful offer of around $1.03 billion in cash to privatise OM Group. Also that month, Apollo won the bidding during an auction for Saint-Gobain’s Verallia glass bottle Manufacturing unit for a rumoured fee of around 2.95 billion.

In February 2016, ADT Corporation agreed to be acquired by Apollo Global Management. Apollo Education Group shareholders approved a merger with Apollo Global Management in May 2016. In June 2016, Apollo Global Management made a successful offer to purchase Diamond Resorts International. Apollo made a successful offer to purchase Rackspace in August 2016.

On December 19, 2017, AGM acquired Mexican restaurant Qdoba for $305 million.

Joshua Harris, a founder of Apollo Global Management, was advising Trump administration officials on infrastructure policy. During that period, he met on multiple occasions with Jared Kushner, President Trump’s son-in-law and senior adviser, said three people familiar with the meetings. Among other things, the two men discussed a possible White House job for Mr. Harris.