After graduating, Ostergaard worked for various companies, including Bang & Olufsen and Philips, designing high-end audiovisual products. In 1991, he founded his own company, the Steen Ostergaard Design Studio, which focuses on the design of consumer electronics and telecommunications equipment.
Over the course of his career, Ostergaard has won several prestigious design awards, including the iF Design Award, the Red Dot Design Award and the IDEA Award. His creations have been exhibited in design museums around the world, including MoMA in New York, the Victoria and Albert Museum in London and the Centre Pompidou in Paris.
Ostergaard is known for his minimalist, functional aesthetic approach and his use of high-quality materials. His most famous designs include the BeoVision MX 7000 television for Bang & Olufsen, the Philips Fisio cell phone and the Konftel 300 conference system for Konftel AB.