For almost 25 years, he was responsible for chemical manufacturing and international production at Janssen Pharmaceutica, and together with Chinese partners, he established Xian Janssen Pharmaceutical. After the opening of China in 1978, their first factory was set up by Joos Horsten in Hanzhong, after which a second and larger factory followed in Xi'an.
From 1992 to 1997, he continued his career at Solvay Pharmaceuticals, a Belgian chemical and pharmaceutical multinational, as Vice-President Technical Affairs, and in 1997 established his own company, as a consultant to Chinese pharmaceutical companies. His contacts led to other companies doing business in China: Xian Thiebaut Pharmaceutical Packaging Co, and Xian Flanders Innovation Services (XFIS).
- "Friendship Award" following the 40th anniversary of the liberation of China, by then Prime Minister Li Peng on 1 October 1989.
- Geerdt Magiels, Joos Horsten (2004). Paul Janssen: pionier in farma en in China. Houtekiet. ISBN 90-5240-827-0.
- Geerdt Magiels, Paul Janssen. Pionier in farma en in China, Houtekiet, 2005.
- "RHEI PHARMACEUTICALS APPOINTS DR. GEERT CAUWENBERGH AS CHIEF EXECUTIVE OFFICER".
- Erik Bruyland. "FLEMISH SMEs pave the way". Trends Magazine.
- "Heart attack of the 66 year old president". Sportwereld. 23 June 2008.
- Alain DECORTE (23 January 2006). "Rescue near for KV Turnhout". Nieuwsblad.
- Dirk (23 June 2008). "Ode to Joos Horsten (1942-2008)". Retrieved 28 April 2009.
- "Hartaanval wordt 66-jarige voorzitter Joos Horsten tijdens een zakenreis in China fataal". Sportwereld. 23 June 2008.
- "Horsten International". Retrieved 2009-04-26.[dead link]
- Harry Schwartz (1989). Breakthrough: the discovery of modern medicines at Janssen. Skyline Pub. Group. ISBN 978-1-56019-100-1.