Rijnhard started his career as an investment banker with First Boston Corporation in New York. He joined Amro Bank in 1983 as Head of Corporate Banking and, in 1988, was appointed to the managing board of Amro Bank. Later, he became Chairman of the investment banking division, which over the last 10 years has grown into one of the world's leading financial organisations. He is presently a partner in Laaken Asset Management NV, and also Chairman of the supervisory boards of Euronext NV, and ARCADIS NV and a Non-executive Board Member of NYSE Euronext Inc and Petrofac Ltd.

His previous appointments include being a Director of Euroclear and Vice Chairman of the Amsterdam Stock Exchange.