He served as executive chairman of book store chain Barnes & Noble and was its largest shareholder from 1971[1] until the sale of the company to the hedge fund Elliott Investment Management in 2019.

[2][3] Under his leadership the company expanded significantly from a single retail location on 105 Fifth Avenue in New York City to a nationwide chain with 600+ stores, which it did with acquisitions and mergers of competing chain stores including his takeover of B. Dalton in 1986, which was supported by a major investment from the Dutch retailer Vendex International and Drexel Burnham Lambert–issued junk bonds.

[12] While at New York University, Riggio founded the Student Book Exchange in 1965 and turned this small bookstore into a leading retailer.

He acquired hundreds of bookstores through the years and launched the Barnes & Noble superstore concept with an in-store coffee shop and spacious reading alcoves.

[13] In 1986, Riggio used junk bonds issued by Drexel Burnham Lambert and a major investment from the Dutch retailer Vendex International to buy B. Dalton; the acquisition made Barnes & Noble the biggest bookseller in the United States.

[14] From 1985, Riggio was Chairman of the Board and majority owner of MBS Textbook Exchange, Inc. based in Columbia, Missouri.

[23] He was active in Democratic Party politics, and served as head of campaign finance for David Dinkins's unsuccessful re-election bid as mayor of New York City in 1993.