After graduating with degrees in applied mathematics and political science from Northwestern, Kingdon served as a financial analyst for real estate investment and advisory company LaSalle Partners and as an associate with management consulting firm A.T. Kearney.

After he received his J.D. and M.B.A. from Virginia, Kingdon founded and served as in-house counsel for Kestrel Ventures, a private equity fund that invested in platform businesses in targeted industries. While there he negotiated the acquisition of another business and formed BroadWing, a regional book distribution and third-party fulfillment company, where he directed finance and operations.